Complex sentence: In the early 19th century, the area around Kaziranga National Park was not well settled, as it was notorious for wild animals, malaria, frequent floods and unpredictable changing of course of the Brahmaputra River.
Split into simpler sentences: In the early nineteenth century, the area around what is now Kaziranga National Park was not well settled. It was notorious for wild animals, malaria, frequent floods, and unpredictable changes of the course of the Brahmaputra River.