Who are Shakyas ?

(Ref. Wikipedia, a free Encylcopedia)

Shakya (Sanskrit:Śākya, Devanagari: शाक्य and Pāli:Sākiya) was an ancient janapada (kingdom) of Iron Age India. The name is derived from the Sanskrit word śakya which means capable, able. In Buddhist texts, the Śākyas are mentioned as a Kshatriya clan. The Śākyas formed an independent kingdom at the foothills of the Himālayas. The Śākya capital was Kapilavastu (Pāli: Kapilavatthu). The most famous Śākya was Shakyamuni Buddha (Gautama Buddha), a member of the ruling Gautama (Pāli: Gotama) clan of Lumbini, who is also known as Śākyamuni (Pāli: Śakamuni, "sage of the Śaka nation").

The accounts of Buddhist texts

The Śākyas are mentioned in the accounts of the birth of the Buddha (Mahāvastu, c. late 2nd century BCE) as a part of the Ādichchas (solar race) and as descendants of the legendary king Ikshvāku (Pāli: Okkāka):

There lived once upon a time a king of the Śākya, a scion of the solar race, whose name was Śuddhodana. He was pure in conduct, and beloved of the Śākya like the autumn moon. He had a wife, splendid, beautiful, and steadfast, who was called the Great Māyā, from her resemblance to Māyā the Goddess. —
Buddhacarita of Aśvaghosa, I.1-2

Annexation by Kosala

Vidūdabha, the son of Pasenadi and Vāsavakhattiyā, the daughter of a Śākya named Mahānāma by a slave girl ascended the throne of Kosala after overthrowing his father. As an act of vengeance for cheating Kosala by sending his mother, the daughter of a slave woman for marriage to his father, he invaded the Śākya territory, massacred them and annexed it.

When was sakya originated?

(Ref. www.Answerlogr.com)

SAKYAS may be the part of Koliya tribe.At the time of Buddha the caste system was in existence.Gautam Buddha's father insisted him to marry a girl from Koliya Tribe only. It shows that Buddha belongs to Koliya tribe. The kolis are traced back to Mohenjadaro and Harappan civilization, their kings MANDHATA.The tribe is spread all over India now. There is no clear description of Shakyas are as kolis as it may be kept away as the community is spread allover India,and in between,all the credits are taken by upper casts.