Complex sentence: The Kingdom of England was a sovereign state to the northwest of continental Europe from 927 to 1707, spanning at its height the southern two-thirds of the island of Great Britain, including modern-day England and Wales, and several smaller outlying islands.
Split into simpler sentences: The Kingdom of England was from 927 to 1707 a sovereign state to the northwest of continental Europe. At its height, it spanned the southern two-thirds of the island of Great Britain, including both modern-day England and Wales, and several smaller outlying islands.