I realised their importance to wargaming the period & wondered how to create some. I looked at internet photos, asked questions on forums etc. The best tip I got was to use bits of actual bushes but experiments in this direction looked awful.
Finally, I decided on wire wool. I made a prototype. I used a MDF base, randomly shaped & with bevelled edges. I put some suitably teased wool on it via the hot glue gun. The base was gritted, then sprayed brown. After drying, I drybrushed the base & added lighter brown high lights to the "thorns".
I'm quite pleased by the result (NB the photo looks very grey when shades of brown are the actual colour).
I've read that Beja warriors did jump over them on occasion. Impressive & I wish my plastic warriors luck.

donald