Thucydides incidentally never makes any mention of Sirras. Basing himself on Aristotle's example of Sirras and Arrhabaeus, N.G.L Hammond concludes that Sirras was a regent to the minor king Arrhabaeus, although Aristotle's quote can also be used to support the case that Sirras was a strategos and Arrhabaeus the king, as Kapetanopoulos argues. At the end of the 5th century BC, Sirras was once again at war with Macedonia over a claim on Lyncestis. Around the end of the reign of Archelaus I of Macedon, ca. 400/399 BC, a new war developed between the two kings over Lyncestis. As in earlier times, Arrhabaeus and Sirras acted together. The results of this war are not known, but later events show that no change happened to the status quo. Sirras' daughter, Eurydice, married King Amyntas III of Macedon in around 390 BC, probably as part of an alliance against the Illyrians, after he suffered his first defeat by them in 393 BC. One of the sons from this marriage was the future Philip II of Macedon.