A couple of my student-worker colleagues were huge pesto enthusiasts. The only ingredient difficult to come by was basil. For a while, we were unsure whether it was available at all. I hadn't tasted it in any of the Yemeni food. Someone made pesto from parsley once, but the taste just wasn't the same.
Hannah did discover that you could buy basil in the produce market we passed every day on the walk home from our daily lunch restaurant. An old lady sold it, sitting on the corner of the market's entrance next to where the motorcycle taxis waited for fares.
Interestingly, Hannah told us that while basil was available it was not primarily used by Yemenis for cooking. Instead, it is used as a fragrant hair decoration.