The red grape variety comes from France. Synonyms are Castet, Engrunat, Gros Machouquet, Gros Verdau, Machouquet, Machoupet and Nicouleau. It should not be confused with the Béquignol Noir or Fer varieties, even though synonyms or morphological similarities seem to indicate this. According to DNA analyses carried out in 2012, it comes from a cross between Gros Cabernet x Camaraou Noir. However, this is based on only 20 DNA markers (see molecular genetics). The vine was found near the commune of Saint-Macaire in the forest around 1870 by a certain M. Nicouleau. A few years later it was allegedly propagated by a M. Castets from the commune of Saint-Pierre d'Aurillac (Gironde). It could also have been named after the parish of Castets-en-Dorthe. Castets was a crossing partner in the six Slovakian new breeds Hron, Nitranka, Rimava, Rudava, Torysa and Váh.