By which year had a large area of land been demarcated as Damin-i-Koh?

NCERT (2026-27): “2.2 The Santhals: Pioneer settlers …
The Santhals were given land and persuaded to settle in the foothills of Rajmahal. By 1832 a large area of land was demarcated as Damin-i-Koh. This was declared to be the land of the Santhals. They were to live within it, practise plough agriculture, and become settled peasants. The land grant to the Santhals stipulated that at least one-tenth of the area was to be cleared and cultivated within the first ten years. …”