An art historian notices that two neighboring cultures both use a similiar style when sculpting horses. This is likley an example if

cultural diffusion or transregional connections.

Cultural diffusion refers to the spread of cultural ideas, practices, or styles from one society to another. In this case, the fact that two neighboring cultures have a similar style when sculpting horses suggests that they have been influenced by each other or have shared artistic practices. They might have interacted through trade, migration, or other means, leading to the transmission of artistic techniques and ideas.

Transregional connections also imply interactions and cultural exchange between different regions. These connections can be through trade routes, cultural exchanges, or shared historical events, allowing for the spread of artistic styles and techniques.

In both cases, the similarity in sculpting horses between the two neighboring cultures suggests a connection or influence between them, either through direct contact or shared historical interactions.