During the Middle Ages, only wealthy people in Europe had chairs. Everyone else had to sit on benches or stools. And even rich people usually had only one chair in their house!
This chair was reserved only for the lord of the house. The lord sat at the table on his chair, while the rest of the family sat on benches, although special guests were sometimes given the chair. So the most important member of a group became known as the chairman.
The Latin word for a bishop’s chair was cathedra; that’s why certain churches became known as cathedrals!