I’m stuck. I’m looking for more information on my great-grandparents and beyond. Isham Williams and Annie (maiden name unknown). See the details I’ve included; can you help me?

Isham Williams married Annie (maiden name unknown) in Kentucky around 1894. Isham was born c. 1871 and Annie (or Ann) was born c. 1876. In 1900 they moved to Kansas. Annie is said to be of Blackfoot descent. This is where the trail runs cold. Does anyone know of how to search further?