Buddhism began in Northern India around the 5th Century BC. It made impressive progress east and south, but only made it as far as Afghanistan to the west. Consequently Western Europe had only minimal contact with it until the eighteenth century.
One noticeable exception is the story of the Buddha. It was told along the trade routes that made their way west. By the time it reached Europe it had mutated into the story of Barlaam and Josaphat. Josaphat is the name Buddha was given, having been derived from Boddhisatva, or "He who shall become Buddha"; according to legend Barlaam was a Christian monk who aided Josaphat in his conversion.
The story became well enough known in Europe for Josaphat to be recognised in the thirteenth century Golden Legend, detailing the lives of the Saints. In the 16th century the Buddha became a fully canonised saint with a feast day on the 27th of November. By the 19th century however the link between the story of Josaphat and Buddha was pointed out and he has since been desanctified.