Complex sentence: In the Himalayas, Schmidt attempted to climb Mount Everest in 1994 and 2008,, summitted Kangchenjunga in 2001, and summited Cho Oyu in 2001,2004 and 2009.
Split into simpler sentences: In the Himalayas, Schmidt attempted to climb Mount Everest in 1994 and 2008. He summitted Kangchenjunga in 2001, and summited Cho Oyu in 2001,2004 and 2009.