Grijalva River, formerly known as Tabasco River, is a 480 km long river in southeastern Mexico. It is named after Spanish conquistador Juan de Grijalva who visited the area in 1518. This river is born in the Sierra de los Cuchumatanes in the department of Huehuetenango in Guatemala, where it is known as Río Seleguá and is one of the most important rivers in t…Grijalva River, formerly known as Tabasco River, is a 480 km long river in southeastern Mexico. It is named after Spanish conquistador Juan de Grijalva who visited the area in 1518. This river is born in the Sierra de los Cuchumatanes in the department of Huehuetenango in Guatemala, where it is known as Río Seleguá and is one of the most important rivers in that country.