 The marriages of Gediminas' sons helped to consolidate the dynasty's power over various territories already within the Grand Duchy, while his daughters' and granddaughters' marriages worked to strengthen Lithuanian relationships with neighboring powers.In 1320 Maria married Dmitri of Tver, ruler of a Russian principality.The marriage took place soon after Mikhail Yaroslavich, Dmitri's father, was killed; his sons were searching for strong allies against Yury of Moscow, their principal competitor for the throne of Vladimir and All Rus'.