By Afghanland.com:

Burhanuddin Rabbani, son of Muhammed Yousuf, was born in 1940 in Badakhshan, a province of Afghanistan. After finishing school in his native province, he went to Darul-uloom-e-Sharia (Abu-Hanifa), a religious school in Kabul. When he graduated from Abu-Hanifa, he went to Kabul University to study Islamic Law and Theology. During his four years at Kabul University he became well known for his works on Islam. Soon after his graduation in 1963, he was hired as a Professor at Kabul University. Rabbani went to Egypt in 1966, and he entered the University of Al-Azhar in Cairo. In two years, he received his masters degree in Islamic Philosophy.

In 1968, Rabbani returned to Afghanistan, where the High Council of Jamiat-i-Islami of Afghanistan gave him the duty of organizing the University students. Due to his knowledge, reputation, and active support for the cause of Islam, in 1972, a 15-member council selected him as head of Jamiat-i-Islami of Afghanistan; the founder of Jamiat-i-Islami of Afghanistan.

In the spring of 1974, police cars came to Kabul University to arrest Rabbani for his pro-Islamic stance, but with the help of his students the police were unable to capture him, and he managed to escape to the country side.

 In 1992 he became President of the Islamic Council of Afghanistan.  a selection of a new president was to take place, Rabbani along with a few of his supported held a meeting and declared himself president for another term. Other Factions controlling Afghanistan at that point were not invited.

In January 1994, Hekmatyar joined forces with Dostum to oust Rabbani and his defense minister, Masood, launching full-scale civil war in Kabul. In 1994 alone, an estimated 25,000 were killed in Kabul; most of them civilians killed in rocket and artillery attacks. One-third of the city was reduced to rubble, and much of the remainder sustained serious damage. In September 1994, fighting between the two major Shi'a parties, the Hizb-i Wahdat and the Harakat-i Islami, left hundreds dead, most of them civilians. Thousands of new refugees fled to Pakistan that year.

by the end of 1994 the rest of the country was carved up among the various factions, with many mujahidin commanders establishing themselves as virtual warlords. The city of Kabul was divided in to neighborhoods controlled by a different faction. Residence could not cross the street to their local market because the opposite side belonged to a different faction and thus you needed documents to cross the street. Women were reduced to slaves and sex toys of the warlords and renegade soldiers. Afghan girls were kidnapped and sold to Arabs and Pakistanis. The economy was shattered; the people were reduced to collect bones in order to trade them for food. Women were not safe in their own homes, thieves ran the streets, the Kabul museum was ransacked and sold to western archeologists and museums, the man with the gun ruled while unarmed civilians were their slaves. The situation around the southern city of Kandahar was particularly precarious: the city was divided among different forces, and civilians had little security from murder, rape, looting, or extortion. Humanitarian agencies frequently found their offices stripped of all equipment, their vehicles hijacked, and their staff threatened. Hekmatyar was awarded the post of prime minister, but still the Burhanuddin Rabbani government lost all authority in Afghanistan. and with popular support of the people, his government was ousted by then very popular Taliban movement

Kabul was captured by the Taliban in 1996. Rabbani set up headquarters in the northern Afghan town of Faizabad and led, with support from Iran and Russia, one of the five anti-Taliban factions.

Stripped of power, he was still recognized as ruler of Afghanistan by the United Nations and most other countries until he formally handed over power to an interim government headed by Hamid Karzai on December 22, 2001.