Complex sentence: Umar Shaikh Mirza died in a freak accident in Aksi fort, North Fergana, when his dovecote, which was built at the edge of the building, collapsed on 19 June 1494, thus making the twelve-year-old Babur the ruler of Fergana.
Split into simpler sentences: Umar Shaikh Mirza died in a freak accident in Aksi fort, North Fergana, on 19 June 1494. It occurred when he was in his dovecote, which was built at the edge of the building, collapsed, thus making twelve-year-old Babur, the ruler of Fergana.