What was the historical Buddha's ethnicity?

Gautama Buddha is traditionally regarded as having a noble body with 32 signs of a Great Man and one of those signs are deep blue eyes. I came across many online discussions about Buddha's ethnicity where some stated that Buddha's family - Sakya - was from Scythian descent. I also met some Ukrainians claiming that Sakyas were precisely from the land that now belongs to Ukraine. Can someone answer the question providing *reliable* sources or evidence?