Complex sentence: Two hundred eighty million years ago, at the beginning of the Permian period, the continents of Laurasia and Gondwana were coming together, forming the supercontinent Pangea.
Split into simpler sentences: Two hundred eighty million years ago marked the beginning of the Permian period in the history of the Earth. The continents of Laurasia and Gondwana were coming together, forming the supercontinent Pangea.