The first mention of the county in the written sources is from 1119 (""cum in Maramorisio tempore venationis venatum ivissemus""). In the 13th century, it was almost uninhabited or very scarcely inhabited. The growth of its population started when the five crown cities (Máramarossziget, Hosszúmező, Huszt, Técső, Visk) were founded in the 14th century. In 1920, after the Treaty of Trianon, the northern part of the county became part of newly formed Czechoslovakia (Subcarpathian Rus'). The southern part (including Sighetu Marmației) became part of Romania.