In fact jungles are so impassable as forests. So why jungles are impassable in DoC? I suppose this is to prevent China conquering India, or vice versa. Moreover the jungle strip in India may be to prevent India to expand easily in the South. However, Mughals should move to South easily. Elephant units are usually used by eastern civs like India, Tamils, Khmers, Thais, Mughals, so they should be able to move their armies through the jungles easily.
Jungle passability doesn't have to do with bigness. Melee units and horses cannot develop formations in jungles properly. Elephants on the other hand don't develop formations, so jungle doesn't bother them.
Jungle passability doesn't have to do with bigness. Melee units and horses cannot develop formations in jungles properly. Elephants on the other hand don't develop formations, so jungle doesn't bother them.