The Arun and Tista Rivers, which flow across the Himalayas, are commonly known as antecedent valleys that overcame the rapid uplift of the Higher Himalayan ranges. To clarify whether the idea of antecedent rivers is acceptable, we investigated the geomorphology of the Himalayas between eastern Nepal and Bhutan Himalayas. The southern part of Tibetan Plateau, extending across the Himalayas as tectonically un-deformed glaciated...