Complex sentence: The two rival royal houses of the fifteenth century were supposedly known by their heraldic badges, the Red Rose of Lancaster and the White Rose of York, from which their long conflict was later called the Wars of the Roses.
Split into simpler sentences: The two rival royal houses of the fifteenth century were supposedly known by their heraldic badges: the Red Rose of House of Lancaster and the White Rose of House of York. Because of the houses' rose badges, their long period of conflict was later called the Wars of the Roses.