Sumyafa' Ashwa al-Yazani, also known as Esimiphaios (Latin: Esimiphaeus) in Syriac and Greek sources, was a vassal king of Himyar, ruling in the 6th century CE under the Aksumite Empire.
He was the son of Lakhni'ah Yarkham, from western Ḥimyar and had been in exile in Aksum, only returning with the Aksumite invasion force.It is not certain that this was the same Sumyafa' Ashwa who was or became king of Himyar.
[4] A fragmentary inscription appears to give Kaleb's full title as the King of Saba', Dhu Raydan, Hadramawt, Yamnat and their Arabs, on Tawdum and Tihamat.
As for the Homeritae, it was desired that they should establish Caïsus [Qays], the fugitive, as captain over the Maddeni [Maʿadd], and with a great army of their own people and of the Maddene Saracens make an invasion into the land of the Persians.
This Caïsus was by birth of the captain’s rank and an exceptionally able warrior, but he had killed one of the relatives of Esimiphaeus and was a fugitive in a land which is so utterly destitute of human habitation.
Thus, Sumyafa' Ashwa is not mentioned in the Martyrionof Arethas, the Bios of Gregentios, the Chronographia of Theophanes of Byzantium or the Chronicle of Michael the Syrian.