When the Moghul emperor Aurangzeb is in his eighties, and the empire in disarray, an Italian living in India (Niccolao Manucci) Predicts appalling bloodshed on the old man's death, worse even than that which disfigured the start of Aurangzeb's reign. The Italian is right. In the war of succession which begins in 1707, two of Aurangzeb's sons and three of his grandsons are killed.

Violence and disruption is the pattern of the future. The first six Moghul emperors have ruled for a span of nearly 200 years. In the 58 years after Aurangzeb's death, there are eight emperors - four of whom are murdered and one deposed.

This degree of chaos has a disastrous effect on the empire built up by Akbar. The stability of Moghul India depends on the loyalty of those ruling its many regions. Some are administered on the emperor's behalf by governors, who are members of the military hierarchy. Others are ruled by princely families, who through treaty or marriage have become allies of the emperor.

In the 18th century rulers of each KIND continue to profess loyalty to the Moghul emperor in Delhi, but in practice they behave with increasing independence. The empire fragments into the many small principalities whose existence will greatly help the British in India to gain control, by playing rival neighbours off against each other.

In the short term, though, there is a more IMMEDIATE danger. During the 1730s a conqueror in the classic mould of Genghis Khan or Timur emerges in Persia. He seizes the Persian throne in 1736, taking the title Nadir Shah.

Later that year he captures the stronghold of Kandahar. The next major FORTRESS on the route east, that of Kabul, is still in Moghul hands - a treasured possession since the time of Babur. Nadir Shah takes it in 1738, giving him control of the territory up to the Khyber Pass. Beyond the Khyber lies the fabulous wealth of India. Like Genghis Khan in 1221, and Timur in 1398, Nadir Shah MOVES on.

In December 1738 Nadir Shah crosses the Indus at Attock. Two months later he defeats the army of the Moghul emperor, Mohammed Shah. In March he enters Delhi. The conqueror has iron control over his troops and at first the city is calm. It is broken when an argument between citizens and some Persian soldiers escalates into a riot in which 900 Persians are killed. Even now Nadir Shah forbids reprisals until he has inspected the scene. But when he rides through the city, stones are thrown at him. Someone fires a musket which kills an officer close to the shah.