Wertheim was probably in the 8th/9th Founded Century. The name of the two-river city is derived from Werder meaning island or elevation in a river.[18] The interpretation of the place name in terms of value has been common since the early 17th century, as in the Wertheim representation in Daniel Meisner's Thesaurus philopoliticus (1623). The first documented mention of Wertheim (whether left or right Mainisch is unclear) took place from 750 to 802 / 779/94 (?). Count Kunibert transfers Eigen zu Wertheim, Biscoffesheim, Kuffese, Rowilenheim, Heringesheim and Kamerdinge to the Fulda monastery (document no. 222, page 320 in the Fulda monastery document book). From the early 12th century, a branch of the Reginbodon family named itself after Wertheim. After the Counts of Wertheim built a castle (Wertheim Castle) to the left of the Main, on the right bank of the Tauber estuary, a new settlement developed below this dominating fortification, which was also given the name Wertheim. In 1192 it was first mentioned as "Suburbium castri Wertheim", around 1200 it was called "oppidum" and in 1244 it was called "civitas".
From 1355 to 1373 the town was ruled by Count Eberhard von Wertheim. In 1363, Wertheim received a document under his aegis for the coinage regime because, according to the document, he supported Emperor Charles IV with "steady trewe and diligent service (...) often without hesitation".[19] During this time, the Count of Wertheim placed the entire county under Emperor Charles IV. The Emperor returned the county to the Count as a fief of the Bohemian Empire. This bondage to Bohemia made the Wertheim counts confidants of the monarchy. The last count of Wertheim was Michael III. He married the eldest daughter of Count Ludwig zu Stolberg, Katharina. Since there was no male descendant from this marriage, the noble family died out and Ludwig zu Stolberg came into the possession of the County of Wertheim. After his death in 1574, the county passed to another son-in-law, Count Ludwig von Löwenstein