Final answer:
Archaeologists believe Indus Valley Civilization cities were corporately governed based on the lack of royal evidence and the existence of advanced urban planning and administrative systems that suggest collective management.
Step-by-step explanation:
Archaeologists suggest that Indus Valley Civilization cities were governed by a corporate structure rather than by kings due to the lack of evidence for the existence of royal structures or palaces and the absence of any depictions of rulers or monarchial regalia.
The uniformity in city planning, with features such as standardized weights and measures, a centralized drainage system, and granaries indicates a high degree of organization and control, which could have been managed by a group of officials or a corporate-like body.
Additionally, the discovery of seals bearing non-royal insignias suggests an administrative system of control that could have been economic in nature, pointing to a possible corporate system rather than a monarchy.