Ukrainians in English were then known as Ruthenians. Are you next going to claim there were no Muslims in 1900, because we called them Mohammedans?
No, in the 10-14th centuries Hungarians called Eastern Slavs like this. It is originally a bastardized word for the Russians based on the misspelling. The term existed until 16th century and was used for Russia and Russians in Latin texts and then disappeared. It was also used by Germans for Baltic Christians until about that time.
It was resurfaced in the 19th century by Austro-Hungary to rally the West Ukrainians against the Russians as if they are different.