Who is Jarsum from Shikasta: Re, Colonised Planet 5: Personal, Psychological, Historical... and what is their importance?

Jarsum is a Giants from Rohandan/Shikastan pre-history. When the Lock breaks, Jarsum refuses to leave, and he leads the other Giants away from the now-broken down ancient cities to their own settlement, where he becomes King. After the Giants die, they become trapped in the nether-regions of Zone Six. Johor visits the Giants occasionally and tries to reason with them. He is unsuccessful.