Due to the transnational nature of conflicts on the African continent, the securing of cross-border areas has gradually emerged as a major issue for peace and security. Although they "are rarely the cause of threats", borders are in fact perceived as "places where dangers crystallize".¹⁰⁹whether they come from turbulent populations or from outside. A seemingly self-evident concept, the border, in its current acceptance, is a historical construction inseparable from the birth of the modern state. It makes its control by means of various tools and strategies, as well as relations with neighbouring states, operational. That being said, geographers distinguish several spatial effects of the border: "that of a barrier, which is its raison d'être, but also that of an interface and that of territory. In the second case, the border merely filters and channels relations between spaces that would exist more diffusely without it.

In the latter, because of the first two functions, it creates a border territory."¹¹⁰. In other words, it is socially structured and conveys its own cognitive networks. Far from being reduced to a reality that is difficult for the central authorities to control, to a dialectic between centre and periphery, the border is therefore a polymorphous object to be apprehended in its multiple aspects. It is a rupture and a link, a functional system whose duality constitutes a resource and a specificity, a territory subject to one (or more) authority (or authorities) exercising its (their) sovereignty in various ways.

Borders and the myth of artificiality

The borders of sub-Saharan Africa are traditionally perceived as arbitrary lines. The Congress of Berlin (1884-1885) is said to have established a "division of Africa on paper that is completely out of step with the sociological and therefore community realities on the ground".¹¹¹. Inherited from the history of colonisation and from European-centred concerns, moreover "envelop[ing] state entities invented [and] created from scratch [...] on the basis of uncertain maps" ... The Congress of Berlin (1884-1885) would indeed have established a "division of Africa on paper, completely out of step with the sociological and therefore community realities on the ground".¹¹²In addition, the borders rarely take into account the socio-demographic or socio-political realities of the African populations: 44% of them are drawn along 'astronomical' lines, 30% follow 'mathematical' lines and 26% are essentially 'facts of physical geography' (rivers, ridges, etc.).)¹¹³. In this context, many populations and ethnic groups are spread over several states, such as the Tuaregs, Fulani or Hausa.

Contrary to an approach that insists on the artificiality of borders, geographer Michel Foucher criticizes "the myth of colonial scars responsible for all evils. "The affirmation of the penalizing nature of African borders is one of the many preconceived ideas," he notes, "as is the affirmation of the absence of pre-colonial political limits or the failure to take into account existing geopolitical realities.¹¹⁴.

Admittedly, there was exogenous division and rapid sharing - more than 70% between 1885 and 1909 - of the African borders.¹¹⁵ -, a priori and according to the balance of power, national assertions and the ambitions of the colonizers. At the same time, however, several boundaries take into account local ethnic configurations or pre-colonial boundaries of a political nature, as well as specific provisions on the use of rangelands and wells. For example, it was with the Sultan that the British signed a protectorate treaty in 1885 in northern Nigeria, under which the Emirs retained their prerogatives in terms of security and tax collection. Secondly, it must be noted that the proliferation of disputes since independence shows that the border network has been appropriated by States that question the principle of borders less than they wish to adjust them.¹¹⁶. One can thus note the merging of the Somalies in 1960, Muammar Gaddafi's attempts to merge the Aozou strip, the violent conflict between Mali and Burkina Faso in 1985 over the Agasher.¹¹⁷or Nigeria's clashes with Chad over some islands in Lake Chad (1983) and with Cameroon over the Bakassi Peninsula (1994-1996).¹¹⁸. Similarly, the independence of Eritrea in 1973 and of Southern Sudan, following the referendum of January 2011, did not really call into question the stability of the territorial reconfigurations with mainly detailed reshuffles.

Camille Lefebvre, in her thesis on Niger, makes a similar observation¹¹⁹. Firstly, the genesis of the borders was marked by the internal dynamics of central Sudan in the 19th century and the processes of negotiations with the people and political authorities. Secondly, the division between France and the United Kingdom is only the starting point for the slow construction of a national community. In this respect, limiting analyses to an unsatisfactory division, without taking into account the national policies that followed, is tantamount to ignoring the fact that borders are a sociological fact that takes on a spatial form, i.e. what people do with them.¹²⁰.

Critique of the routes: from colonizers to anti-colonialism

Criticism of the early layouts and the pre-state configuration of the 18th and 19th centuries came from the colonizers themselves, engaged after the conquest phase in a succession of reshuffles and adjustments between powers or constituencies in the empires. It developed after the European treaties of 1919-1923, particularly in the teachings and textbooks of the colonial school, which no longer structured the space into areas of influence and administrative divisions, but promoted a new deThis is particularly true in the teachings and textbooks of the colonial school, which no longer structure space into areas of influence and administrative divisions, but promote a division based on physical ("natural regions") and human ("ethnic areas") geography, thereby removing politics and essentializing ethnicity. After 1945, this idea of artificial borders became one of the main arguments of anti-colonialism. This was first of all the case in France, under the impetus of Georges Balandier.¹²¹then in a second phase with the affirmation of the pan-Africanist current carried by Kwane N'Krumah.¹²².

Borders as opportunities and resources

African borders are not obstacles. The non-coincidence of borders with major linguistic areas and economic basins even constitutes resources. Nigerian naira is thus commonly used in the Nigerian region of Diffa, economically polarised by Maiduguri. Fulani is spoken in about fifteen countries, Swahili in about ten others, Mandingo in five... It is the same for the Touareg, Toubou or Arab populations of the Sahel-Saharan strip. Through their history and displacements - particularly as a result of droughts or rebellions generating flows towards Libya and Algeria - the Tuareg, Toubous or Arab populations of the Sahel-Saharan strip have been displaced.¹²³ - they have a mastery of local dress codes, identities and networks in their settlement areas and circulation spaces.

The dynamism of internal circulation also refers to intra-regional socio-economic dynamics. In the first place, the African space is marked by complementarity between coastal and inland regions; between livestock breeding areas and food production areas; between agricultural production areas and urban markets. The Gambia, Togo, Benin and Djibouti thus constitute warehouse states with land corridors oriented towards the hinterlands. It should be noted, however, that the flows are not limited to this orientation alone: Togo and Benin are in a situation of strong interdependence in relation to Nigeria. Similarly, the East-West Abidjan-Lagos corridor accounts for 65% of the economic activities in the ECOWAS area, serves 35 million people and ensures the transit of 47 million people per year.¹²⁴. On the other hand, border disparities "crystallize and materialize possibilities for accumulation and social regulation that have become essential in the context of the decline in the living conditions of populations and the tightening of conditionalities imposed" by structural adjustment policies.¹²⁵. The smuggling of subsidised everyday consumer goods between Algeria and Mali, or the dynamism of the border area between Nigeria and Niger, illustrate this border effect.This border effect is based on agro-economic (dry and wet zones), demographic (full and empty), monetary, regulatory and customs differentials.

As a result, cross-border areas with high trade intensity have been formed, driven by networks of merchants residing in the major urban centres and having spread to neighbouring countries. This dynamism of the trans-state region is not specific to sub-Saharan Africa. However, it has had several consequences, two of which are worth mentioning. On the one hand, the development of these flows has led, within States, to extreme dependence on external economies, with the corollaries of disarticulation of the weakest sectors and weakening of territorial control. On the other hand, under the double effect of external pressure to harmonize tax and customs policies and internal tensions in border societies, the development of these flows has led to extreme dependence on external economies, with the corollary of disarticulation of the weakest sectors and weakening of territorial control.¹²⁶The strategies for exploiting the border effect have shifted to other products (gold, diamonds, fauna and flora, drugs, livestock theft, ransom, kidnapping...) and other areas. "The accelerated internationalisation and criminalisation of economic, financial or migratory networks and flows between the African continent and the countries of the former Soviet Union has led to the creation of a new international network of border crossings.The accelerated internationalisation and criminalisation of economic, financial or migratory networks and flows between the African continent and European, Asian or American economic areas bear witness" - Daniel Bach observes - "to the effectiveness of the substitution strategies put in place. »¹²⁷Some communities, such as the Nigerian Igbos, have also been able to use their history, their presence on other continents and their beliefs as an example to insert themselves into these transnational commercial - and criminal - networks.¹²⁸.

States and border control

Before addressing the issue of border control by States, it is important to briefly consider the actors involved in the cross-border movement of goods. Indeed, trade involves a myriad of economic and political-administrative agents: smugglers, regional merchants, some of whom are close to the authorities, etc. The issue of border control by States is also important.¹²⁹One of the main characteristics is that it goes beyond the categories usually used, such as between legal and illegal activities, criminal groups and State representatives. In West Africa, border police and customs are thus regularly presented as the main predators in border areas, as are several of the suspectedIn West Africa, border police and customs are thus regularly presented as the main predators in border areas, just as many of the people suspected of having made money from international drug trafficking are presented locally as first-rate campaign financiers when they have not themselves obtained (bought?) elective office.¹³⁰. To put it another way, official and unofficial circuits are inextricably linked, just as the registers of the inter-State and intra-State are inseparable.¹³¹.

This recall is not without consequences. The control of an area is far from being reduced to a count of border posts in relation to the length of the border, the number of people affected and actually present at these posts, or the existence of a functional link with the capital. The absence of structures materializing the presence of the State does not mean the absence of control by State representatives, the power and its networks, or alternative authorities, whether officially recognized or not. As the geographer Julien Brachet reminds us, there are "forms of territorial control" based on "agricultural and pastoral organization", or on "access to natural resources (wells and pastures)".¹³². Secondly, state agents are present, even if they are few in number and "their activities are not very much in line with their official missions, or even totally illegal".¹³³In the second place, state agents are present, even if they are few in number and "their activities are not very much in line with their official missions, or even completely illegal", and alongside the "dressed corps" there are substitutes and sometimes very efficient networks of informers.

Talking about "porous borders" therefore leads to a misrepresentation. This expression reflects the image of "insufficient control of vast portions of the Sahara and the Sahel", thus forming a "grey, uncontrolled and uncontrollable zone".¹³⁴ to the detriment of taking into account alternative forms of control based on intelligence or recourse to non (or para) state actors¹³⁵. For example, on the outskirts of the ancient Wolof kingdoms of western Senegal (13th-18th centuries), the border areas of the confines were sparsely populated and entrusted to Fulani camps responsible for guarding herds and watching over the borders.¹³⁶. Another example, in the Sahara and the Bornou region, the border in the 18th and 19th centuries was the subject of negotiations between political powers, of the exercise of sovereignty, and of the right to vote. or predation on a line accepted and recognized as such, or monitored through a "back-boundary arrangement". The Sultan of Agadez had thus set up a system of control in inhabited areas in order to tax caravanners forced to pass through certain wells and inhabited villages to obtain supplies.¹³⁷.

109 Laurent Bossard, quoted in Bérangère Rouppert, "La gestion des espaces transfrontaliers au Sahel: entre espaces de vie et zones grises", GRIP, 29 December 2014, p. 2.

110 Entrée " Frontière ", in Jacques Lévy and Michel Lussault, Dictionnaire de la géographie et de l'espace des sociétés, Paris, Belin, 2003 edition, p. 384-385. In addition to this definition, the frontier can also be analysed through the spatial practices of its inhabitants or of those who cross it, their representations, the practices of the actors, the networks that structure it.

111 Bérangère Rouppert, art. cit., p. 2.

112 Karine Bennafla, "La fin des territoires nationaux? État et commerce frontalier en Afrique centrale", Politique africaine, 1999/1, n°73, p. 25-49, p. 27.

113 Pierre Kipré, "La crise de l'État-nation en Afrique de l'Ouest", Outre-Terre, 2005/2, n°11, p. 19-32, p. 23.

114 Michel Foucher, Frontiers of Africa. Pour en finir avec un mythe, Paris, CNRS éditions, 2014, pp. 10-11.

115 Ibid, p. 14.

116 These adjustments are notably linked to the gaps in the archives left by the colonizers.

117 The judgment handed down by the International Court of Justice on 22 December 1985 decides in favour of a delimitation of the colonial snapshot based on the search for tangible signs and on the basis of the intentions of the administrators of the circles. In other words, "it is a question of precisely delimiting the colonial route" (Ibid., pp. 23-24).

118 A peace agreement was signed between Cameroon and Nigeria in 2006, following a settlement by the International Court of Justice. These conflicts between Chad, Cameroon and Nigeria were not very deadly.

119 Camille Lefebvre, Frontières de sable, frontières de papier, Paris, Publications de la Sorbonne, 2015.

120 Georg Simmel, Sociology. Étude sur les formes de socialisation, Paris, Presses universitaires de France, 1999, p. 607.

121 George-Léon-Émile Balandier (1920-2016) is an ethnologist and sociologist, founder, among others, of the Centre for African Studies.

122 Michel Foucher, op. cit., pp. 20-21.

123 The Lamhars of Mali, for example, during the droughts of the 1970s and 1980s, and then the Tuareg rebellions of the 1980s, and then the Tuareg rebellions of the 1990s.The Lamhars of Mali, for example, during the droughts of the 1970s and 1980s, and the Touareg rebellions of the 1990s and 2000, lost most of their livestock, while their low level of schooling did not allow them to find a job in the administration or to establish the necessary contacts to set up projects with foreign NGOs. They therefore turned to trade with Algeria, relying on their diaspora present in that country and the language community with other Arab groups (Charles Grémont, Les Touaregs Iwellemmedan de l'Ouest (1647-1896). A political ensemble of the Boucle du Niger. Alliances, power relations, identities, Université Paris I-Sorbonne, history thesis defended in 2007; Judith Scheele, "Tribes, states and fraud: the Algerian-Malian border region", Études rurales, 2/2009, 184, pp. 79-94).

124 Michel Foucher, op. cit., p. 35.

125 Daniel Bach, "Border Constraint and Resources in Sub-Saharan Africa", Revue Internationale de Politique Comparée, Vol. 2, No. 3, 1995, pp. 533-541, p. 537.

126 Among the factors of tension are the following: crisis of pastoral territories under the impact of droughts and the cultivation of new areas; dysfunctions of local authorities and questioning of the authority of customary chiefs; social inequalities and gerontocracies (national and local); divisions between younger and older people; and the lack of a common vision of the future.These factors are also at the root of the resurgence of coupeurs de route in the Lake Chad basin in the 2000s. The young Fulani who then take up arms see banditry as a means of revolt, access to freedom and a way to quickly obtain capital. See : Christian Seignobos, "Le phénomène zargina dans le nord du Cameroun. Coupeurs de route et prises d'otages, la crise des sociétés pastorales mbororo", Afrique contemporaine, 2011/3, No. 239, pp. 35-59.

127 Daniel Bach, art. cit, p. 540.

128 On Nigerian mafias, see: Stephen Ellis, This Present Darkness. A History of Nigerian Organised Crime, Oxford, Oxford University Press, 2016 (and the book review by François Gaulme, "Stephen Ellis, This Present Darkness. A History of Nigerian Organised Crime", Contemporary Africa, 2016/3, No. 259, pp. 171-174).

129 These merchants are linked to the authorities through political support and clientelist logic. The networks they run are structured according to mainly economic and secondarily ethnic logics.

130 Interviews, members of civil society, Mali and Niger, 2016 and 2017.

131 Daniel Bach, "Régionalisme et régionalisation à travers le prisme de l'aire saharo-sahélienne", in Laurence Mafaing and Steffen Wippel (eds.), Les relations transsahariennes à l'époque contemporaine, Paris and Berlin, Karthala and ZWO, 2004, pp. 457-479, p. 471.

132 Julien Brachet, "Sahel et Sahara: niincontrôlables-ni-incontroles ", CERI, 10 July 2013 (http://www.sciencespo.fr/ceri/fr/content/dossiersduceri/sahel-et-sahara-ni-incontrolables-ni-incontroles) .

133 Ibid.

134 Armelle Choplin and Olivier Pliez, "Reconstructing the image of the territories of the Sahara and the

Sahel ", Mappemonde, n°103, 2011/3.

135 The expression "porosity of borders" also leads to neglecting the analysis, and therefore the importance, of the role played by social relations or the interdependence of different social groups.The term "border porosity" also leads to neglecting the analysis, and therefore the importance, of the role played by social relations or economic interdependencies structuring border areas, not without being potentially useful for state authorities wishing to attract external financing.

136 Michel Foucher, op. cit. p. 20.

137 Camille Lefebvre, op. cit. pp. 93-94.