Index is a town in Snohomish County, Washington, United States. The population was 155 at the 2020 census. Prior to settlement by European Americans, the Skykomish people had many villages along the Skykomish River between Sultan and Index. One large and important village of the bəsx̌əx̌əx̌alč band was at x̌əx̌aʔusalʔtxʷ, the area now called Index. …Index is a town in Snohomish County, Washington, United States. The population was 155 at the 2020 census. Prior to settlement by European Americans, the Skykomish people had many villages along the Skykomish River between Sultan and Index. One large and important village of the bəsx̌əx̌əx̌alč band was at x̌əx̌aʔusalʔtxʷ, the area now called Index. At the village were several longhouses, including a large potlatch house. x̌əx̌aʔusalʔtxʷ was the base camp for people traveling into the Cascades for hunting and gathering.