Complex sentence: The largest single ethnic group is people of Bangladeshi descent, which constitute 38 per cent of the area's population, every year since 1999 the Baishakhi Mela is celebrated in Weaver's Field, Bethnal Green which celebrates the Bengali New Year.
Split into simpler sentences: The largest single ethnic group is people of Bangladeshi descent, which constitute 38 percent of the area's population. Every year since 1999 the Baishakhi Mela is celebrated in Weaver's Field, Bethnal Green which celebrates the Bengali New Year.