Thrones in general
Thrones have been the symbol of kings and gods since the dawn of human civilization. The throne was used for coronation ceremonies and were used to lift the king up above all people present.
Thrones were since then directly associated with royal power and are still used in phrases as "to ascend the throne" and "to be seated upon the throne"
Thrones in ancient cultures and religions
The Greeks (as learned from the works of Homerus) were known to place additional (empty) thrones in the royal palaces and temples so that the gods could be present when they wished to be. The most famous of these thrones was the throne of Apollo in Amyclae. The Greek thrones were influenced by eastern civilizations since contact between the Greeks and these civilizations were made around the 7th century BC.
The Hittites even considered thrones to be gods themselves!
An order of angels called thrones is included in some Christian beliefs about the classification of angels.
Thrones and the Bible
The Bible mentions a lot of thrones. God was seated upon a throne and so was King Solomon (as Gods representative on earth): "Moreover the king made a great throne of ivory, and overlaid it with the best gold" (Kings 10:18)
In Medieval times the throne of Solomon was associated with Mary (Ivory means purity, Gold means divinity and the six steps of the throne were the six virtues) Jesus promised his Apostles that they would sit upon "twelve thrones", judging the twelve tribes of Israel (Matthew 19:28).
Johnss Revelations states: "And I saw a great white throne, and him that sat on it, from whose face the earth and the heaven fled away"