Historically focaccia was unleavened, the recipe rises naturally in the right climate, and this gives a further clue to its origins, the further inland one goes the less dense the air becomes, and considering so much of the inland Mediterranean is quite mountainous we can speculate that it was inland people who first created focaccia. Contrast this with Phoenician people who originated in what is now coastal Lebanon and coastal Syria, and then spread throughout the Mediterranean by 1100 BC weren’t known to eat bread with the same properties as focaccia. In coastal areas a small amount of yeast need to be added to make the bread rise, otherwise a traditional flat bread is the result.