The supply chain of a seemingly innocuous cash crop - sesame - has intersected with transnational conflict dynamics, exacerbating tensions between Ethiopia and Sudan.Late 2020 saw the beginning of the devastating war in Tigray and the occupation of a disputed region on the Ethiopia-Sudan border - Al Fashaga - by the Sudanese army. These shocks disrupted settled patterns of land ownership and control in both Ethiopia's volatile north and Sudan's borderlands, historically the heart of the sesame and oilseed production that is economically vital to both countries. These seemingly harmless cash crops are now embedded in local, subnational and national political contestations in both countries. Sesame value chains are being reshaped, with power and profits being used to entrench the grip of political and armed actors who are reinforcing new patterns of land control and driving informal and illicit trade - impacting the coping mechanisms of local communities and threatening to fuel further conflict. Regional rivalries drive contestation over the Ethiopia supply chain Internal borders between most of Ethiopia's regions are marked by boundary disputes, which often degenerate into violent conflict. The most important is between the Tigray and Amhara regions. Since the war began in 2020, the Amhara region has annexed vast areas of western and southern Tigray, which the Amhara region claims were taken from them by Tigray 30 years ago, after the Tigray People's Liberation Front (TPLF) dominated ethnic coalition came to power.Conflict has exacerbated a steady decline in formal revenues from sesame exports, dropping over $115 million from 2016 to 2021. Ethiopia's exports of spices, oilseeds and pulses brought in over half a billion dollars in 2021, roughly a quarter of the country's total export revenues and second only to coffee. The sector has been rocked by the war in the north, which accounted for much of Ethiopia's sesame production, with an estimated 500,000 hectares of sesame fields taken out of cultivation during the 2021 growing season. Conflict has exacerbated a steady decline in formal revenues from sesame exports, dropping over $115 million from 2016 to 2021. Alongside falling production, the previously integrated value chain has been disrupted and decentralized by political fragmentation and land competition between Amharas and Tigrayans. Before the war, the agricultural sector in Western Tigray/Welkait was dominated by Tigrayan business interests, through the TPLF's regional endowment fund EFFORT, a business conglomerate including subsidiaries such as Guna Trading House, and Hiwot Agricultural Mechanization. The taking of the area by Amhara forces in late 2020 saw the control over agricultural supply chains shift to actors from the Amhara region, amid contestation between regional officials, businessmen and security actors, backed by political elites. Thousands of displaced ethnic Tigrayan inhabitants of the area have been replaced by ethnic Amharas, enticed to settle there by the Amhara regional government's offer of grants and leases for land which promise better livelihoods. The sesame they farm is now largely exported through informal and illicit channels, with profits used to reinforce de facto regional control. But there is also contestation within the Amhara region over the land and sesame supply chain between sub-regional elites from Gojjam, Gondar and indigenous Welkaites. Welkaites, who were marginalized under TPLF rule, believed that by aligning themselves with powerful Amharas they would reclaim land and influence. But this has not been fully realized, with the local administration reliant on Amhara region subsidies, rather than the federal budget. With little support from the federal government, local Welkait officials are strengthening their ties with Eritrea. The Ethiopian government's pursuit of peace with Tigray may lead it to turn away from the Amhara region, which could result in a renewed showdown between Amhara and Tigrayan forces.At the national level, regional contestation over the control over Western Tigray/Welkait feeds into shifting political alliances between the Amhara, Tigrayans and Oromo which threaten the sustainability of the peace agreement struck between the federal government and TPLF in November 2022 - despite efforts by the government to defer the thorny issue. While the constitutional return of the land to Tigray remains unlikely anytime soon, there is a feeling that Amhara control over Western Tigray/Welkait is no longer certain. The Ethiopian government's pursuit of peace with Tigray may lead it to turn away from the Amhara region, despite their alliance during and before the war, which could result in a renewed showdown between Amhara and Tigrayan forces. The prospect of losing territory could also heighten Amhara nationalist claims on Al Fashaga - the loss of which was partly offset by gaining Western Tigray/Welkait - leading to renewed conflagration with Sudan, outside of federal direction. Eritrea's presence and alliance with Amhara militias remains a concern, given Asmara's demonstrable ability to inflame tensions. Sudan's securocrats battle over resources to entrench political power The war in northern Ethiopia was also used opportunistically by the Sudanese Armed Forces (SAF) to take control of the fertile Al Fashaga borderland. This roughly 250 sq km area had been awarded to Sudan when the boundary was initially demarcated by the British in 1903, a ruling that remained contested by Ethiopia. An uneasy truce had seen Ethiopian farmers cultivate the land under nominal Sudanese administration; a settlement that collapsed in 2020 when thousands of predominantly Amhara farmers were evicted. Local Sudanese farmers have also lost out - with some not compensated for the loss of lands to their own military, with land given to people from other parts of the country, and through lost relationships with Ethiopian farmers, labourers and investors. The Sudanese military now allegedly controls more than 90 per cent of the disputed areas and security-linked companies and investors have moved into the lucrative sesame sector, re-routing the supply chain, which used to flow largely through Ethiopian markets. These companies are connected to Sudan's Military Industrial Corporation, a vast conglomerate of business subsidiaries controlled by SAF - which is headed by General Abdel Fattah al-Burhan.Competition between Sudanese security actors fuels volatile political rivalries, and further entrenches military control of economic resources. The commander of the paramilitary Rapid Support Forces, General Mohamed Hamdan Dagolo (or Hemedti), also has interests in agriculture, through his family business Al-Junaid. Both sit at the top of Sudan's Sovereign Council. Hemedti's competition with Burhan has seen him develop relations with Ethiopia's prime minister - counter-balanced by recent rapprochement between Abiy and Burhan - as well as senior Amhara leaders, including over business activities. Moreover, competition between Sudanese security actors fuels volatile political rivalries, and further entrenches military control of economic resources, undermining civilians at a time when pro-democracy forces are seeking to restore a reform-minded government. One of the key challenges for a new civilian government will be to quickly build up a domestic revenue base to compete with the economic heft of the country's prominent security institutions, which will demand taking on military-controlled holdings in civic sectors such as agriculture, including sesame. Informal and illicit trade reinforces conflict dynamics This context has driven the informalization of trade, with cash crops such as sesame increasingly exported outside of formal channels and connected to other illicit cross-border activities between Ethiopia and Sudan. Indications are that sesame production in Western Tigray/Welkait has recovered significantly during the current 2022/23 harvest season. However, rather than contributing much needed currency to soften Ethiopia's forex crisis, the Amhara elite-controlled supply chain is primarily being used to secure a variety of regional interests. Sesame fetches up to double the price per quintal (100kgs) in Sudan that it does in Ethiopia. The resulting smuggling effectively reinforces Sudanese security sector control over the supply chain. There are also suggestions that shipments of sesame and other goods between Amhara region-controlled Western Tigray/Welkait to Eritrea have been used as payment in kind for Eritrean forces training and support of Amhara militias, further encouraged by exchange rate benefits. Sesame fetches up to double the price in Sudan that it does in Ethiopia. The resulting smuggling effectively reinforces Sudanese security sector control over the supply chain. It is the first time that there has been a trading route between Ethiopia and Eritrea in over twenty years, but it is mostly outside the control of the Ethiopian government. Rather than flowing into government coffers, revenues are used for the purchase of arms, drugs, and second-hand clothes – all which can be sold for higher profits. Arms sales from Sudan to Ethiopia have soared since the start of the war, with some Ethiopian farmers using their land in Al Fashaga as collateral to buy weapons for protection and Amhara militiamen smuggling arms to rival Tigrayans for a premium. The complexity of the sesame supply chain – including its connection to conflict, politics, and illicit trade – highlights the difficulty facing policymakers over what interventions could be supported in cross-border contexts. Tackling the roots of conflict supply chains requires working holistically at the local, national, and – crucially – transnational levels. Cooperative cross-border measures focused on building economic alternatives and more effective governance – such as by restoring trade routes and securing shared operation of farmlands in Al Fashaga – should run alongside policies that support trust-building between Ethiopia and Sudan. This would simultaneously bolster efforts to secure a durable political settlement in Ethiopia, including by reducing tensions between Amhara and Tigray over Western Tigray/Welkait. If successfully embedded, such policies could provide the basis for longer-term regional stability.