The conquests of Muhammad of Ghur (1175-1206) established the first great Muslim empire in Northern India, stretching from the Punjab to Bengal. Muhammad was the younger brother of Ghiyas ud-Din, who for most of his life was Sultan of Ghur. Muhammad acknowledged his brother's superior rule, and served him loyally, before finally inheriting the sultanate after his brother's death in 1202/3. During the perid of his greatest successes in India Muhammad was his brother's viceroy in Ghazni, and spend much of his time campaigning in Afghanistan or eastern Persia.
Muhammad first entered India in 1175, when he defeated the Karmathian Muslim rules of Multan, in upper Sind. His first attack on a Hindu ruler came in 1178, when he advanced south from Multan into Gujarat to attack Raja Bhimdev II. After a difficult journey across the desert Muhammad's army suffered a heavy defeat at Kayadara, a village near Mount Abu, and Muhammad was forced to retreat back across the desert. This victory saved Gujarat from conquest by Muhammad or his subordinates, although the capital city of Anhilwara was sacked in 1197.
His next target was Khusrau Malik, the last Ghaznavid ruler, whose capital was at Lahore. Khusrau was a weak ruler who relied on support from the Khokhar tribe to stay in power. The basic outline of Muhammad's campaign against Khusrau is clear, although some aspects of the dating are less so. In 1179 or 1180 Muhammad took Peshawar from its Ghaznavid governor. His first attack on Lahore came in 1180 or 1181, and was probably with the support of the Khokhars. Khusrau Malik was forced to surrender his best elephant and his oldest son as a hostage. Muhammad then moved on to build a fortress at Sialkot.
This was too close to home for the Khokhars, who switched sides and supported Khusrau Malik in an unsuccessful siege of Sialkot. This brought Muhammad back to India, for a second siege of Lahore. In 1186 Khusrau Malik was captured, probably after coming out of Lahore under a flag of safe conduct to negotiate terms. He and his son were sent west to Muhammad's brother, where they were later executed, probably in 1192 as part of the prepatarions for a campaign in the west.
With the last Ghaznevid presence eliminated Muhammad turned his attentions east, towards the Ganges plains. In the winter of 1190-91 he captured the fortress of Bhatinda, part of the kingdom of Prithviraha Chauhana III of Delhi and Ajmer. Prithviraha responded by raising a vast army, and winning a major victory over Muhammad at the first battle of Taraori or Tarain (1191). While Prithviraha concentrated on the siege of Bhatinda, Muhammad raised a new army, and in the following year won his won victory at Taraori (1192). Prithviraha was killed in the battle, and large parts of northern India were exposed to conquest.
After this victory Muhammad returned to Ghazni, leaving Qutb al-din Aibek as his viceroy in India. Aibek served Muhammad just as loyally as Muhammad served his brother. It was Aibek who captured Delhi during the winter of 1192-93, and after Muhammad's death it would be Aibek who became ruler of his Indian empire.
Muhammad returned to India in 1193 (1194 in some sources) to deal with a threat from Jaichand Gaharwar, the ruler of Benares and Kanauj. Jaichand was killed in a battle at Chandwar, and his kingdom soon became part of Muhammad's expanding empire. Benares itself was sacked, and a number of temples destroyed.
After this victor Muhammad once again returned to Ghazni leaving Aibek in command in India. At some time in 1195-97 Aibek returned to Gujarat, looting the capital, although he was unable to conquer the area. A series of minor campaigns occupied the next few years in northern India allowing Aibek to secure Muslim rule, before in 1203 Aibek conquered Kalinjar.
Bengal was conquered by another of Muhammad's subordinates, Muhammad bin Bakhtiyar Khalji. In around 1202-1204 he captured Nabadwip, the capital of Lakshman Sen, forcing Lakshman to flee south. Muhammad bin Bakhtiyar Khalji ruled Bengal from Lakhauti until 1206, when he was murdered during the retreat from an unsuccessful invasion of Assam.
The beginning of the end for Muhammad of Ghur came in 1205, when he suffered a massive defeat at Andkhui at the hands of Shah Ala ud-Din Mohammed of Khwarezm. News of this defeat spread across Muhammad's empire, triggering widespread revolts. Things only got worse when Muhammad ordered Aibek to deal with the revolt in India, leaving himself free to focus on the war against Khwarezm. This helped convince the rebels that Muhammad must have been killed at Andkhui. The Khokars, along with a number of other tribes, and led by Rai Sal, defeated the deputy governor of Multan, plundered Lahore and blocked the road from the Punjab to Ghazni.
This convinced Muhammad that he would have to deal with the revolt in person. Late in 1205 he reached Peshawar, before engaging the Khokars in a day-long battle that ended in victory only after Aibek arrived with reinforcements. Muhammad had successfully regained control of his Indian empire, and prepared for a new campaign in the west, but in March 1206 he was murdered on the banks of the Indus, either by a band of Khokars or by Isma'ili assassins.
By the time of his death Muhammad had succeeded his brother, and ruled a massive empire that included modern Afghanistan, Pakistan and northern India. This empire quickly split into its component parts. Aibek took control of the Indian part of the Empire, although probably didn't proclaim himself as Sultan. That would be left to his successors, but despite this Aibek is generally seen as the founder of the Sultanate of Delhi, and of the Slave Dynasty that would rule until 1290.