It also depends whether they cut grooves at all. If you simply taper the very tip sharply, and you can use a running loop (a sort of slipknot) in the string and it will tighten up against the taper. No need for grooves, hence no need for nocks. That's the best way to tiller bows too, as you're not deciding on a bow length or string position before the bow is made.
You can also tie the string on in various ways, much like African bows were braced. There's not really any limit to draw weight with these methods, so it's quite plausible, and works with virtually any draw weight.