Alma 56:3

Behold, two thousand of the sons of those men which Ammon brought down out of the land of Nephi: Now ye have known that these were a descendant of Laman, which was the eldest son of our father Lehi.

There were 2,000 sons of the men that Ammon brought from the land of Nephi. You know that these people came from Laman, who was the oldest son of our father Lehi.

“Two thousand sons of the men Ammon brought out of Lamanite territory have joined us. You know they’re descendants of Laman, our ancestor Lehi’s oldest son.”