 The specific feature in Japan has been the fact that these marriages have been soon incorporated as elements of tradition which controlled the marriages of later generations, though the original practical alliance had lost its real meaning.A repeated pattern has been an imperial son-in-law under the influence of his powerful non-imperial father-in-law.Beginning from the 7th and 8th centuries, Emperors primarily took women of the Fujiwara clan as their highest wives – the most probable mothers of future monarchs.