That's going to depend on how loosely you define the instrument. The plucked psaltery is one of the oldest instruments known. The bowed psaltery as we know it doesn't appear to be very old.
In 2008 I began researching the origin of the Bowed Psaltery, information wasn't easy to find. I looked on and off for quite a few years and then just let it go.
While working on the new website I came across a very thorough history that begins with the plucked psaltery. It's the best I've read and doesn't include some of the popular but unsupported anecdotes I've come across.
The article can be found on Appalachian Strings. The author, Thomas Cook, builds hammered dulcimers and bowed psalteries. Here is a direct link to the history https://www.appalachianstrings.net/a-history-of-the-hammered-dulcimer-1
It's certainly possible a bow was put to the psaltery in ancient times but documentation has not been uncovered and/or shared. In the end, ancient or modern, I am just going to enjoy my Bowed Psaltery.