The Zamba-Toh is similar to a gigantic sword, on the end of a gigantic bo or pole. It is over 7ft long and some weighed more than 100 pounds. It originated in China and was later used in Japan as well. The weapon is quite heavy and large, it takes a lifetime of dedicated practice to reach any level of proficiency with it. It was designed to kill a horse in one sweep, sending the rider to the ground. The word Zanbatou literally means horse-slaying sword. The no-dachi however was probably the better choice for this job, if not as bad-ass.
The Zamba-Toh was never in wide use but has become popular through video games and anime. If you do a search on google you will find just about every page is about Seung Mina from Soul Calibur. If you search for Zanbatou you will find pages about Sanosuke from Kenshin.
The Zamba-Toh or Zanbatou
I think it is important to note that this is indeed the same word. Zamba-Toh is phonetic while Zanbatou represents the characters used to spell it out.