By definition, a tropical bamboo would not survive in your Zone; further, most tropical bamboo are not runners. Beyond that, your description is not much help as it could apply to dozens of different species. It's probably some common form of Phyllostachys. Pictures, including closeups of the nodes, could help in narrowing things down.

Ok so it's this

Since it has yellow grooves probably Phyllostachys aureosulcata.

I agree...it does look like Yellow Groove (Ph. aureosulcata), which is also probably the most common bamboo grown in the U.S.

Oh ok. Well I just looked that name up and it seems to like full sun. This bamboo patch doesn't really get too much sun and theres another one in my shady part of the backyard too. And its been there for I think 11-12 years. How is it surviving without enough sun?

Bamboo is much less demanding than many other plants. I had a grove of Yellow Groove for 30 years that did just fine in the shade of 80' tall fir trees. The bamboo never got direct sun. However, one year I decided to get some more light into the yard by limbing-up the firs about 25'. The next year the Yellow Groove put out some new culms that were at least a third taller than they had ever been before. The bottom line is that you have a completely healthy clump of Yellow Groove that would probably get somewhat bigger/taller if it were in full sun all day. You should think of the "full sun" label for bamboo as meaning it can tolerate full sun, not that it needs it.

Phyllostachys are native to southern Chinese forests where the running habit enables them to migrate into spots that have better light.

Oh good to hear! You said 30 years, did it die??

No, I moved, but it was still doing fine last I saw it. It was large when I bought the house; it's probably been in that location at least 60 years. Individual culms on most bamboo last about 7 years, but there are new ones each year. If the plant gets its light, water, and nutrition needs met it will continue indefinitely. Remember: bamboo is not a shrub or tree; it's in the grass family.

Oh thats even better to hear. So not only it is such a tough plant but it lives very long. Do you know any Japanese native phyllostachy varieties?

Not a Phyllostachys, but what about Pseudosasa japonica?

It is technically a runner but less aggressive than most. I do believe it is Japanese (also known as Japanese arrow). Hardy in NJ/Zone 7 (at least in my yard).

Probably most Phyllostachys are native to Japan. There are only three bamboos that are native to the U.S., and I believe they are all from the Arundinaria genus.

Well I kinda want an aggressive spreading bamboo to make a privacy screen hedge sometime next year. So should I stick to phyllostachys? Or any other aggressive bamboo you'd recommend? And I thought phyllostachys were native to China?

The hundred plus species of Phyllostachys are not limited to one country.

Any Phyllostachys should work well if you want it to spread. Don't expect it to expand uniformly and form a perfect hedge, and do expect it to take a number of years. Also figure out how you intend to limit its spread to areas of your yard where you don't want it, and to your neighbors' yards.