In 999 the Abbot of Moutier-Grandval Abbey gave his extensive landholdings around Lake Biel, including where La Neuveville would be founded, to the Prince-Bishop of Basel.

At that time the region was known as Nugerol and over the next centuries the Bishop of Basel and the Counts of Neuchâtel often quarreled over the land.

In 1283 the Prince-Bishop Henry von Isny began to have Schlossberg Castle built on the slopes of the Jura Mountains.

To further solidify his claims, around 1310, the next Prince-Bishop, Gérard de Vuippens, founded the town of La Neuveville.

The town and castle pushed the borders of the County of Neuchâtel to the eastern side of the Ruz de Vaux stream.