The Noldor used horses effectively during the Siege of Angbad. They also had famous steeds descending from Valinor. Nienor, Morwen and their escorts got horses from Thingol, as they went to Nargothrond, and Eöl also had some.
But it seems that the majority of the Sindar of Beleriand were woodland or seafaring people, and the naugrim, who taught them weapon-crafting and war, also preferred infantry combat.
Did the Grey-Elves of Beleriand tame and breed horses, and did they use them to travel and for war, before the coming of the Noldor and the rising of the Sun?
If the answer is yes, how broadly; if no, were there even wild horses? (Since the ecosystem of Middle-earth worked on savings flame, and many living beings slept the Sleep of Yavanna, the diversity of the species was probably limited.)