What people eat can't tell you everything about a time or a place - but it can tell you an awful lot. What foods were available in that place? Which foods were scare and which were abundant? How do those people think about food in general? What are the common flavor profiles? How does a (generic) dish go together? What constitutes a meal? Under what circumstances did people eat with others, and what kinds of meals are served then? What influenced changes in food over time (immigration, technology, work patterns)?
An exemplar of this is Olive Trees and Honey by Gil Marks, a collection of recipes from Jewish communities around the world. The Jews are particularly interesting in this regard since they were expelled from so many European countries over time. What this means is that they brought their food traditions to friendly countries, incorporated foods and cooking techniques from those new places into their traditional cuisine (simultaneously introducing foods and techniques to the natives of the area). When it became dangerous to stay, the Jews moved to another region - where they introduced their traditional cuisine, which now included influences and recipes from their last "host" country's cuisine, to the natives of the new region. And they did this over and over again.
So far I've cooked only a couple of recipes from this cookbook, but I've read every word. It is a beautiful and fascinating collection that's worth buying even if you choose to read it instead of cook from it.
For a snapshot of different cultures' food without the recipes, I recommend What the World Eats by Faith D'Aluisio and Peter Menzel. This beautiful book consists of photographs of 25 families in 21 countries around the world, each photographed surrounded by food they will eat in a typical week. The differences are startling and enlightening and absolutely fascinating.
