The earliest historically documented representative of the family is Keno Kenesna,[1] who in 1309 was one of the three consules et advocati terrae Nordensis.
In Brokmerland the tom Broks maintained a Redgerhof in Engerhafe, which gave the owner the right to exercise the office of judge.
Widzeld died in 1399 in the church at Detern from a fire caused by a blaze started by warriors of the Archbishop of Bremen, the Count of Oldenburg and other allies.
Keno's son Ocko II inherited such large territories that he was able call himself the chief of East Frisia.
In the following period, however, there were disputes between Focko Ukena and Ocko tom Brok, which turned into open acts of war.
After the first victory of the East Frisian chief Focko Ukena over Ocko II at Detern in 1426, Focko allied himself with the Bishop of Münster and numerous East Frisian chiefs against Ocko, who was limited to Brokmerland and defeated him on 28 October at the Wild Fields between Oldeborg and Marienhafe for good.