Ahmad came to power as a result of a plot against his brother Shaikh Hussain Jalayir. In 1382 he departed from Ardabil, which he had been given control of, and took Tabriz; Husain was captured and executed. Ahmad's other brothers, Shaikh 'Ali and Bayazid opposed him; Husain's former amir, 'Adil Aqa, had Bayazid proclaimed sultan in Soltaniyeh, while Shaikh 'Ali prepared to leave Baghdad and march on Tabriz. To secure his position, Ahmad requested the assistance of the Black Sheep Turkmen. Shaikh 'Ali fell in battle against the Turkmen; within two years Ahmad was also able to neutralize Bayazid.
In the spring of 1384 the Chagatai amir Timur attacked the Jalayirids. Although Sultan Ahmad was not captured, his subordinates in Soltaniyeh failed to defend the town and Timur took it with a minimum of resistance. Timur gave the town to 'Adil Aqa, who had defected to him, before retiring from the campaign. Ahmad then sent an army to retake Soltaniyeh, but 'Adil Aqa successfully defended it. In the midst of Timur's absence, Sultan Ahmad had to deal with an invasion by Tokhtamysh, Khan of the Golden Horde. Tokhtamysh's troops swept down into Azerbaijan, devastating the land, and Tabriz was sacked in around the end of 1385. Ahmad himself had escaped to Baghdad through the aid of his ally, Izz al-din Shir of Hakkari. The raid of Tabriz had significantly weakened Ahmad's position; he consequently could not combat Timur when he returned in 1386. Tabriz was taken by the Chagatais in the summer; its citizens had to pay a heavy tribute. 'Adil Aqa collected the tribute but was executed by Timur, who suspected him of corruption. Azerbaijan from this point on remained in the control of the Timurids, as Ahmad could not recover the province. In 1393 Timur renewed the war with Sultan Ahmad. Near the end of August, he arrived at Baghdad, where Ahmad was residing. Deciding that defending the city was impossible, Ahmad fled and traveled to Mamluk Syria, and was granted asylum by Sultan Berkuk. Although Baghdad was forced to pay a ransom and many captives, including Ahmad's son Ala al-Daula, were taken with Timur when he left the city, most of the citizenry were left unharmed. A Sarbadar, Khwaja Mas'ud Sabzavari, was given control of the city. In 1394 Sultan Ahmad returned to Baghdad; Khwaja Mas'ud withdrew his forces instead of fighting. As a result, Ahmad was able to regain control of the city for the next six years. He grew increasingly unpopular, however, and in 1397 or 1398 an unsuccessful conspiracy was hatched against him. Feeling unsafe in Baghdad, he left the city and requested the assistance of the Black Sheep under Qara Yusuf. The Turkmen arrived at the city, but Ahmad had a difficult time in preventing them from plundering Baghdad, and he eventually turned them back. In 1398 Timur's son and governor of Azerbaijan, Miran Shah, attempted to take Baghdad but Ahmad successfully resisted him. In 1399 a Georgian raised the siege of the town of Alenjaq, which the Timurids had been attempting to take for more than a decade. The leader of the Georgian army, one of Ahmad's sons, came to Baghdad, but rebelled and was killed. When Timur returned from campaigns in the east in 1400, Sultan Ahmad feared that he would be attacked and left Baghdad; he returned for a short while but then left again, taking refuge with the Ottomans. In May 1401 a group of Chagatais sent to Baghdad by Timur encountered resistance; although more Timurid troops were sent the city commander, unaware that they were Timur's forces, refused to give in. Timur himself soon arrived and Baghdad was subjected to a forty-day siege; when it still refused to surrender he order the city stormed. Once it was taken, nearly all of the men, women and children were massacred and most of the public buildings were destroyed. The destruction was so widespread that Timur did not even bother to install a governor. Soon afterwards, however, Sultan Ahmad yet again returned to Baghdad and began to rebuild it. Although a contingent of Chagatais nearly captured him, he came back a few months later in 1402 with the Black Sheep Turkmen ruler Qara Yusuf, who had also sought refuge with the Ottomans. Their friendship, however, did not last, and Qara Yusuf expelled Ahmad from the city. Ahmad fled to the Mamelukes a second time, who however imprisoned him out of fear of Timur. In 1403 Qara Yusuf was driven out of Baghdad by the Timurids, and sought asylum with the Mamelukes, who imprisoned him also. Together in prison, the two leaders renewed their friendship and struck an agreement with each other; Ahmad would retain Iraq, while Qara Yusuf would take over Azerbaijan.
Overthrow by the Black Sheep Turkmen
When Timur died in 1405, Nasir-ad-Din Faraj, the Mamluk Sultan of Egypt, released Sultan Ahmed, who returned to Baghdad, and Qara Yusuf, who took up residence in Tabriz. In spite of their agreement, however, it did not last. Ahmed wanted to regain Azerbaijan as a result he attacked the Kara Koyunlu. He managed to occupy Tabriz for a brief time, but was defeated in August 1410. He was then captured by Qara Yusuf and executed; Ahmed's son Ala-ud-Daula, who had been released by the Timurids, was also killed. Ahmed's nephew Shah Walad Jalayir briefly succeeded him in Baghdad but the Kara Koyunlu took the city a year later. Jalayirds were pushed south into lower Iraq, ruling over the towns of Hillah, Wasit and Basra until extinguished by the Kara Koyunlu in 1432, bringing an end to the dynasty.