'Theirs' in the Bible

And sent letters to all the divisions of the kingdom, to every division in the writing commonly used there, and to every people in the language which was theirs, saying that every man was to be the ruler in his house, and that this order was to be given out in the language of his people.

Then on the thirteenth day of the first month, the king's scribes were sent for, and they put in writing Haman's orders to all the king's captains and the rulers of every division of his kingdom and the chiefs of every people: for every division of the kingdom in the writing commonly used there, and to every people in the language which was theirs; it was signed in the name of King Ahasuerus and stamped with the king's ring.