Complex sentence: In 1349--50 alone more than half the population of East Anglia died, and in 1369 East Anglia--whose farming economy had collapsed in the wake of the plague--was struck by famine.
Split into simpler sentences: In 1349--50 alone, more than half the population of East Anglia died. In 1369, East Anglia, whose farming economy had collapsed in the wake of the plague, was struck by famine.