Nur ibn Mujahid was the son of Wazir Mujahid ibn 'Ali ibn 'Abdallah ad-Duhi Suha, one of the cavalry commanders of Imam Ahmad ibn Ibrahim al-Ghazi who himself was the son of Garaad Ali who was from a well established noble family.^[7] Mujahid married Ahmad’s sister, from which marriage Nur was born. According to several oral traditions recorded by Enrico Cerulli, Nur ibn Mujahid was a Somali that hailed from the Marehan subclan of the greater Darod clan.^[8][9] But Mohammed Hassen states Nur's father was a chief of the Harari people.^[10] The Royal Chronicle of Gelawdewos' considers Nur to be "from the tribe of the Suhawyan", which according to Solomon Gebreyes Beyene could be the name of an Afar or Somali subclan.^[11][12]

When Imam Ahmad ibn Ibrahim al-Ghazi, who had led the Muslim conquest of the Ethiopian Highlands, was killed in 1543, the Muslim forces fell back in confusion to Adal. The dead leader’s widow, Bati del Wambara, undertook to renew the fortunes of the Kingdom. She inspired her people to take revenge and the Adalites, believing that they Abyssinians were vulnerable, invaded the highlands in 1548. This ended in catastrophe when they were repulsed by Gelawdewos's vassal, Fanu'el, and Gelawdewos later arrived in the region upon where he ravaged the country for five months.^[13]

Nur was promoted to Emir between 1548 and 1550, and married Ahmad ibn Ibrahim al-Ghazi's widow, Bati del Wambara. He was recognized by the people of Harar, the Somalis and the widow of Ahmad as the Sahib al-Fath al-Thani, or "Master of the Second Conquest". She had reportedly made him promise to devote to avenging the death of Ahmad before agreeing to marry him. ^[14][15][16] Contemporary Harari records describes Nur as a very religious ruler who abstained from every act forbidden by the Sharia and likewise wanted his people to follow his example in their lives, explicitly prohibiting un-Islamic behavior among the nobility.^[7]

Nur departed on a jihad (holy war) to the eastern Ethiopian lowlands of Bale and Dawaro. This venture was unsuccessful, Nur was defeated and the Abyssinians then advanced into Adalite territory. However, this defeat was not mortal and Adal soon recovered.^[17]

In 1559, urged on by his wife, Nur once again took the offensive and invaded Fatagar. Gelawdewos, who was in Gojjam, sent his cousin Hamalmal to Harar hoping to force the Muslims back. But Nur held on, hoping to deal the Abyssinians a decisive blow in their own country. Hamalmal was able to enter Harar without any significant resistance, capturing and executing Sultan Barakat ibn Umar Din. In the meantime, Gelawdewos, with a larger army attacked emir nur with smaller army .^[18] Gelawdewos was defeated and killed by Nur at the Battle of Fatagar. Following this victory, Nur crossed over into Wej province to loot the palace and the capital of the deceased emperor before promptly returning to his country.^[19][20] The decapitated head of Gelawdewos was brought to Harar where it was put on display for the people to witness.^[21]

Despite this victory, the following years were very difficult for Harar. The Oromos who had been migrating north invaded the Adal Sultanate and annihilated Nur's army at the Battle of Hazalo. The invasion was accompanied by carnage on an appalling scale and according to Bahrey, there had been "no such slaughter since the Oromo first invaded". This was followed by a mass migration which sent different groups fleeing from their ancestral homes.^[22][23]

Most of the Muslim population fled to the walled city of Harar. The Oromos then occupied and settled on the lands of the Hararghe highlands which had been abandoned by the local population.^[24][25] After the Oromos had settled in the surrounding countryside of Harar, the city experienced a severe famine. J. Spencer Trimingham narrates "Emir Nur exerted every effort to help his people to recover, but after every respite the Oromo would again descend like locusts and scourge the country, and Nur himself eventually died of the pestilence which spread during the famine."^[26]

Some historians consider Nur as the last witness and protagonist of Islamic greatness in the Horn of Africa.^[27] In fact a later Harari Arabic poem praising Nur says: "The city of Harar sparkles with holy men; and, especially with the rightful Imam of the pious. Well deserved she is, to draw the hems of her raiment, 'cause he who has built her, is the annihilator of the infidels."^[28] Harari documents from the time also give him the prestigious title of Amir al-Mu‟minin.^[29]