There are some bamboo which are that height as mature plants, but I'm curious what bamboo that would be in your Zone. Are you absolutely sure it's bamboo? Could you post a picture or describe it better? In particular, do the culms/stalks die back in the winter, or does it simply defoliate? How old is this planting?

I looked it up and believe it to be a fargesia murielae. I'm looking for companion plants. Any suggestions?

F. murielae is a nice one. Bamboo coexist with almost anything. I have quite a few bamboo -- albeit in a more temperate climate, Zone 8 -- and I have been successful with ferns, various groundcovers, cotoneaster, and smaller flowers like marigolds, California poppies, and smaller-size daylilies and irises. Some of those may be too big in scale for your bamboo now, but murielae is quite hardy and should size up to a respectable height in coming years.

Plants with contrasting large leaves. Otherwise, frequent companions for Fargesias in the wild are spruces and rhododendrons.

My neighbor in the back of my house has an excessive growth of bamboo used as a wall and/or property divider. The bamboo is nice but I would like to know how do you manage the roots for growing other plants? The roots have extended quite a distance and within this distance, I would personally like to include various plants. I have previously tried gardening but the bamboo roots kills the plants. What could I do to prevent the bamboo roots in killing my plants?