Complex sentence: There has been in a decline of Hinduism, Buddhism and Sikhism in the areas that now constitute the country of Pakistan which was formed in 1947 happened for a variety of reasons, and even as these religions have continued to flourish beyond the eastern frontiers of Pakistan.
Split into simpler sentences: There has been in a decline of Hinduism, Buddhism and Sikhism in the areas that now constitute the country of Pakistan which was formed in 1947. This happened for a variety of reasons even as these religions have continued to flourish beyond the eastern frontiers of Pakistan.