The Mumakil of Harad (also called Oliphants and
Mumàk) are huge beasts somewhat resembling elephants. Some brief
reports suggest that the mumakil did not actually originate from Harad,
but came from the neighboring savannahs of Khand.
The Haradrim, men of Harad, train these large beasts
for war, securing large platforms on the backs of the animals and drive
them to battle. In the Battle of the Pelennor Fields they were used to
pull large towers and siege engines into line (RotK chp.6). The immense
beasts served as a rally point for the evil forces due to the fact that
the Rohirrim horses swerved around the beasts.
The main road for the Haradrim to Gondor passes
through Ithilien; it is here that Samwise Gamgee came across an
Oliphant as it rampaged through the trees.
see also Duilin (Man) and Derufin