Analysis of information sources in references of the Wikipedia article "Eurydice I of Macedon" in English language version.
Philip's mother is traditionally regarded as Illyrian ... She may have been from the royal house of Lyncus in Upper Macedonia
We do not really know why Eurydice, the daughter of the Illyrian (?) Sirrhas and the grand-daughter of Arrhabaeus of Lyncus, was preferred as the mother of his successors.
Sirrhas has been identified as either a Lyncestian or an Illyrian. Two ancient sources call Eurydice an Illyrian (...) and a third, a passage preserved in Plutarch's essays (...), probably does so as well. Such an ethnic designation could refer to her general line of descent and not specifically to Sirras. ... Given the current state of evidence, it seems reasonable to conclude that Eurydice had both Illyrian and Lyncestian (through her grandfather) blood and that, though her father may well have been an Illyrian allied with the Lyncestians, his ethnicity remains uncertain.
οἱ δὲ Λυγκῆσται ὑπ᾽ Ἀρραβαίωι ἐγένοντο, τοῦ Βακχιαδῶν γένους ὄντι· τούτου δ᾽ ἦν θυγατριδῆ ἡ Φιλίππου μήτηρ τοῦ Ἀμύντου Εὐρυδίκη, Ἴρρα δὲ θυγάτηρ