The Huari's coastal rivals

For Covey, 50 the Cuzco vales had taken on some Huari colonies; he implies the Huari sites were foreign here. These Cuzcian towns survived the Huari collapse to the Fourth Age - they did NOT retreat to the hills. The same might be said for Chanca, 150 km west (p. 54). But a pre-Inca palace in Cuzco was a "thirtieth" the size of contemporary still-Third-Age palace at Chan Chan of the Chimú culture.

Huari was expansionist and imperial in a way Tiahuanaco wasn't. I don't know where's evidence of Huari attacking Tiahuanaco. It may be that Huari saw Chanca and Cuzco both as difficult-enough. If the Huari hold was light, and trade with Tiahuanaco unhindered, this may explain why Cuzco memory didn't recall a difference. One wonders if Chanca might have remembered more about the Huari in particular.

Huari at 600-1100 AD overlaps Moche (up to 700) and Chimú (Chan Chan founded 900). I am unsure why the 700s and 800s AD are absent from Wikipedia for the coast. Did the Huari annex postMoche coastal sites, inspiring and encouraging Chimú to rally around Chan Chan ...? Sicán, also, was post-Moche coastal. Records are better here (at least for Wiki). It too doesn't really take off until 900 AD.

To me, this looks like the Huari started off with some hegemony over disunited coastal polities, profiting from the collapse of Moche culture. But the postMoche sites rallied, asserting their independence. The Huari never did exert force over Tiahuanaco. The coastal sites were very rich sites; Tiahuanaco didn't matter so much, but losing the coast hurt. The Huari for whatever reason couldn't reorganise from - say - Quito, as Huayna Capac did. So it collapsed.

As to why Tiahuanaco also fell at this time, I know less. Maybe the lack of trade from the north. Over the Fourth Age, I do see that Tiahuanaco's old region of hegemony is succeeded by Aymara chiefdoms. It may well be that the Inca royal family started as one of these. Chanca, westward, strikes me as purely Quechua.

UPDATE 5/23/21: Huari's decline AD 900-1100 overlaps the Amazon's.