Mamia acceded to the throne by blessing of King Bagrat III of Imereti, his royal suzerain.
Mamia, having secured for his troops a free passage from the atabeg of Samtskhe, traversed Ghado mountain, advanced into Kartli and defeated David X at Mokhisi.
The latter fell back to his capital of Tbilisi and was setting a counter-attack in motion, when a dignitary, sent by Gurieli for parley, persuaded the king to join Mamia and Levan of Kakheti at a peace summit at Mukhrani.
The first encounter with the fiercely defending Zygii was won by the allies, but, on the next day, many battle-fatigued Mingrelian nobles defected their lord at the instigation of Tsandia Inal-Ipa, an Abkhaz.
Later, Malachias I Abashidze, Catholicos of Imereti and Abkhazia, went to the Zygii and ransomed the survivors and bodies of those who died.