Complex sentence: The basin comprises mountainous regions of the Himalayan ranges with dense forests, sparsely forested Shiwalik hills, the fertile Gangetic plains, the Central highlands lying to the South of the Great plains consist of mountains, hills and plateaus intersected by valleys and river plains.
Split into simpler sentences: The basin comprises mountainous regions of the Himalayan ranges with dense forests, as well as the sparsely forested Shiwalik Hills and the fertile Gangetic Plains. The central highlands lying to the South of the Great Plains consist of mountains, hills and plateaus intersected by valleys and river plains.