Complex sentence: He was made High Sheriff of Berkshire at the age of only eight, was styled Count of Poitou from 1225 and in the same year, at the age of sixteen, his brother gave him Cornwall as a birthday present.
Split into simpler sentences: He was made High Sheriff of Berkshire at the age of only eight, was styled Count of Poitou from 1225. In 1225, at the age of sixteen, his brother gave him Cornwall as a birthday present.