In the Kalasaya compound, there are stellae with markings for ceremonial purposes.
ArtToday.com
Monoliths in Courtyard, Tiwanaku
Since the residents were agrarian, it may be that the statues represent religious figures.
Tiwanaku, Bolivia: Stellae in Courtyard
From Bonnie Hamre, About.com
Andes and Altiplano Regions of Bolivia
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