Complex sentence: Pratchett's first novel, "The Carpet People", was published in 1971; after the first Discworld novel, "The Colour of Magic", was published in 1983, he wrote two books a year on average.
Split into simpler sentences: Pratchett's first novel, "The Carpet People", was published in 1971. The first Discworld novel, "The Colour of Magic", was published in 1983, after which he wrote two books a year on average.