Ethiopian – Adal war The Ethiopian – Adal war was a military conflict between the Ethiopian Empire and the Adal Sultanate that took place from 1529 until 1543 . Background . Islam was introduced to the Horn of Africa early on from the Arabian peninsula , shortly after the hijra . In the late 800s , Al - Yaqubi wrote that Muslims were living along the northern Somali seaboard . He also mentioned that the Adal kingdom had its capital in the city , suggesting that the Adal Sultanate with Zeila as its headquarters dates back to at least the 9th or 10th centuries . According to I . M . Lewis , the polity was governed by local dynasties consisting of Somalized Arabs or Arabized Somalis , who also ruled over the similarly - established Sultanate of Mogadishu in the Benadir region to the south . Adal ' s history from this founding period forth would be characterized by a succession of battles with neighbouring Abyssinia . Between 1529 and 1559 , the Somali military leader Imam Ahmad ibn Ibrihim al - Ghazi defeated several Ethiopian emperors and embarked on a conquest referred to as the " Futuh Al - Habash " ( " Conquest of Abyssinia " ) , which brought three - quarters of Christian Abyssinia under the power of the Muslim Sultanate of Adal . With an army mainly composed of Somalis , Al - Ghazi ' s forces and their Ottoman allies came close to extinguishing the ancient Ethiopian kingdom . However , the Abyssinians managed to secure the assistance of Cristóvão da Gama ' s Portuguese troops and maintain their domain ' s autonomy . Both polities in the process exhausted their resources and manpower , which resulted in the contraction of both powers and changed regional dynamics for centuries to come . Many historians trace the origins of hostility between Somalia and Ethiopia to this war . Some scholars also argue that this conflict proved , through their use on both sides , the value of firearms such as the matchlock musket , cannon s and the arquebus over traditional weapons . Course of the war . In 1529 , Imam Ahmad ' s Adal troops defeated a larger Ethiopian contingent at the Battle of Shimbra Kure . The victory came at a heavy cost but it solidified the Somali forces ' morale , providing proof that they could stand up to the sizable Ethiopian army . The victories that gave the followers of Imam Ahmad the upper hand came in 1531 . The first was at Antukyah , where cannon fire at the start of the battle panicked the Ethiopian soldiers . The second was on 28 October at Amba Sel , when troops under the Imam not only defeated but dispersed the Ethiopian army and captured items of the Imperial regalia . These victories allowed the Somalis to enter the Ethiopian highlands , where they began to sack and burn numerous churches , including Atronsa Maryam , where the remains of several Emperors had been interred . The country was looted by the Ahmad ' s forces , who destroyed several Christian monuments and oppressed the non - Muslim Amhara and Tigray . Dawit II died in 1540 and his heir was captured by the forces of Imam Ahmad ; the Empress was unable to react as she was besieged in the capital . In 1543 , Ethiopian guerrillas were able to defeat the Somalis with the help of the Portuguese navy , which brought 400 musketeers led by Cristóvão da Gama . Although da Gama was captured in the Battle of Wofla , and later killed , in 1543 Ahmad himself was killed and his army destroyed in the Battle of Wayna Daga , with the help of surviving Portuguese musketeers . The Ethiopian / Portuguese force consolidated their victory by ambushing and destroying a second force under one of the Imam ' s subordinates . This turned the war around . The surviving Somalis were forced to withdraw from Ethiopia , leaving both kingdoms severely weakened . Aftermath . Mohammed Hassan has plausibly argued that because the participants in this conflict weakened each other severely , this provided an opportunity for the Oromo people to migrate into the lands south of the Abay east to Harar and establishing new territories .