The Dutch Chess Championship was officially established in 1909, although unofficial champions stretch back to the 1870s.
Official championships
The official championship was established in 1909 as a biennial, twelve-player, round-robin tournament. As of 1970, the top five finishers were seeded into the next championship, one player was nominated by the Selection Committee and six came from preliminary qualifying tournaments. Three regional qualifying tournaments of eight to twelve players each were held over four weekends. Grandmasters were not required to qualify to play in the championship. In 1970, annual championships were instituted. In 1935 a championship for women was established.
References
Dutch Chess Championship Wikipedia(Text) CC BY-SA