That the Arya tribes, in particular the Puru/Bharatas were in conflicts with other Arya tribes and possibly amongst themselves is amply evident through various verses in Mandala VI.
RV 6.019.13 Through these thy friendships, God invoked of many! may we be victors over every foeman. Slaying both kinds of foe, may we, O Hero, be happy, helped by thee, with ample riches.
The above verse talks of “both” kind of foes. The Dasas were one of them, the other must have been Arya tribes. RV 6.033.03 provides clear vindication of the other tribe being Arya.
RV 6.033.03 Both races, Indra, of opposing foemen, O Hero, both the Arya and the Dasa, Hast thou struck down like woods with well-shot lightnings: thou rentest them in fight, most manly Chieftain!
Inference that the conflicts may have occurred within Puru tribe, let alone amongst rival Arya tribes is found in several verses.
RV 6.019.08 Indra, bestow on us the power heroic skilled and exceeding strong, that wins the booty, Wherewith, by thine assistance, we may conquer our foes in battle, be they kin or stranger.
RV 6.025.03 Those who array themselves as foes to smite us, O Indra, be they kin or be they strangers,- Strike thou their manly strength that it be feeble, and drive in headlong flight our foemen backward.
RV 6.044.17 Therewith enraptured, Hero, slay our foemen, the unfriendly, Maghavan be they kin or strangers, Those who still aim their hostile darts to smite us, turn them to flight, O Indra, crush and kill them.
RV 6.019.08, RV 6.025.03 and RV 6.044.17 all refer to foes that might be kin or strangers. The Sanskrit word used is a variant of “jAmayaH” meaning sibling.
As the power and influence of the Arya tribes and in particularly the Puru tribe grew, so did the scale of the conflicts. The Hariyupiyah War between an alliance of Puru-Anu tribes on the one side and the Vrcivan clan of the Yadu tribe on the other was perhaps the first large scale war in ancient times. Several generations later came “Dasaranjana War” or the War of Ten Kings – an internecine war between the allies of King Sudas, a descendant of Divodasa and his enemies, an alliance of 10 Kings from other Arya tribes.