In the case of Athens, even resident aliens (metoecci) did not have this right to marry Athenians.
Epigamia was also a way of formalizing the relationship between different nations. Typically, an epigamia agreement would allow the adoption of the nationality of the country of residence, for the spouse as well as children. For example, Athens granted epigamia to Euboa in the 5th century, a very rare case.
In 303 BCE, Seleucus I led an army to the Indus in India, where he encountered Chandragupta. The confrontation ended with a peace treaty, and "an intermarriage agreement" (Epigamia, Greek: Επιγαμια), meaning either a dynastic marriage or a more general agreement for intermarriage between Indians and Greeks. Accordingly, Seleucus ceded to Chandragupta his northwestern territories as far as Arachosia and received 500 war elephants (which played a key role in the victory of Seleucus at the Battle of Ipsus):