'Thresholds' in the Bible

Shallum the son of Kore, the son of Ebiasaph, the son of Korah, and his relatives of his father’s house, the Korahites, were over the work of the service, keepers of the thresholds of the tent; and their fathers had been over the camp of the Lord, keepers of the entrance.

All these who were chosen to be gatekeepers at the thresholds were 212. These were enrolled by genealogy in their villages, whom David and Samuel the seer appointed in their office of trust.