I echo Andrew's comments with some additions. First, did you clean this sword up? Both the handle and blade look like they may have been and that would effect the estimation of age somewhat. The vegetal or kanok motif at the hilt is definately a Thai design almost identical to one used as an example in the "Silverware in Thailand" book I have. As Andrew says the handle is turned on a lathe which makes it 20th century and probably the later part. What intriques me is the blade has some heft and the heavy brass ferrule (is that a crack or a seam) say to me that it was meant to be used. The length would put it in the made for fighting category and not the utility blade category. The blade profile and handle are consistent with many depicted in statuary throughout Thailand. The scabbard throws me off, while I've seen a very few Thai blades with this type of scabbard , none have been on the more modern blades. As Andrew noted we believe this is more a Khmer feature but those generally have an angle at the blade hilt junction.
I have seen the modern blades currently made in Aranyik and the high-end functional ones have all had a machined steel ferrule with vestigal guard. The low-end stuff almost invariably has a thin brass ferrule with a thin brass cap nailed down around the blade as do those from Lampang. I have not seen the high-end blades from Lampang or Uttaradit though I'm told they have them. If you had said you picked this up in the northeast along the Thai/Cambodian border everything would fit but I know of no makers out that way (though my knowledge of makers in Thailand is by no means all encompassing)
You have a very nice functional Thai sword with a unique scabbard configuration that appears to be well made. Nice start
. In your email you said that you picked it up in Chatuchak market, if you don't mind and can recall which dealer did you pick it up from and what were his wares like (antiques, amulets, general merchandise...)
Welcome to the the forum!