Short answers, pulled from the story.
The East End lies east of the Roman and medieval walls of the City of London and north of the River Thames. Aldgate Pump, on the edge of the City, is regarded as its symbolic starting point. Its northern and eastern boundaries are not officially defined, though the River Lea is sometimes treated as the eastern limit.
The first known written record of the East End as a distinct entity comes from John Strype's 1720 Survey of London, which described London as consisting of four parts, including "That Part beyond the Tower".
The East End has been home to successive waves of migrants including Huguenot refugees, Irish weavers, Ashkenazi Jews, lascars from the Indian subcontinent, Africans from the Guinea Coast, Chinese communities in Shadwell and Limehouse, and, from the late 1950s onward, a large Bangladeshi population from Sylhet. Bangladeshis now form 32 per cent of Tower Hamlets' population as recorded at the 2011 census.
On the 4th of October 1936, between 3,000 and 5,000 uniformed members of the British Union of Fascists, led by Oswald Mosley, attempted an anti-semitic march through the East End. Up to 100,000 East Londoners turned out to oppose them. Clashes at Tower Hill, the Minories, Gardiners Corner, and Cable Street forced the fascists to abandon the march.
The London Docks closed in 1971, and the last of the East End's docks, the Royal Docks, closed in 1980. The London Docklands Development Corporation was established in 1981 to oversee regeneration of the vacant land.
The Whitechapel Bell Foundry opened in 1570 and operated until 2016, making it what was described as the oldest manufacturing company in the United Kingdom. It cast many of the world's most famous bells, including Big Ben, the Liberty Bell in Philadelphia, and Bow Bells. It also jointly developed the Olympic Bell used in the opening ceremony of the 2012 London Games, described as the largest harmonically tuned bell in the world.