From A Wiki of Ice and Fire
Tolos is a port city that lies on the northwest coast of Slaver's Bay. It is connected by Valyrian roads to Mantarys and Bhorash. To the west lies the city of Elyria on its island. The Black Cliffs lie between it and Bhorash.
Tolosi slingers are the best slingers in the world, and they throw soft lead balls in place of stones. Tyrion Lannister notes that their lead balls do vastly more damage than the smooth stones other slingers use, and more than any bow as well. Hizdahr zo Loraq has kin in Tolos.
A Dance with Dragons
Daenerys Targaryen of Meereen sends missions to Tolos hoping to find new friends to the west to balance out the enmity of Yunkai in the south. The Tolosi reply to Dany’s request for an alliance by proclaiming her a whore and demanding that she return Meereen to its Great Masters. Tolos allies with Yunkai.
References and Notes