Complex sentence: As a result, until the 19th century the precise location of the battle was unknown when Stepan Nechaev came up with what he believed was the exact location of the battle and his hypothesis was accepted.
Split into simpler sentences: As a result, until the 19th century the precise location of the battle was unknown. In the 19th century Stepan Nechaev came up with what he believed was the exact location of the battle and his hypothesis was accepted.