According to Charles Perry the evolution of Baklava started from the unleavened bread baked on a saj which was layered with a filling, this evolved into a pastry made of 8 layers of dough and filled with nuts, then finally into the multilayered phyllo dough baklava which was developed by the Ottoman Turks in the Topkapi palace kitchens.
Nawal Nasrallah, an expert on Iraqi cuisine and history, says that a pastry called lauzeenaj was made in the 10th century had many of the characteristics of the baklava of today. It was made with raqeeq al riqaq, the thinnest of thin breads and was stuffed with almonds and sugar, flavored with mastic and rose water and fried in almond oil. Nasrallah says that waraq, very thin pastry wrappers were described in the 10th century Bagdadi cookbook (by IbnSayyar al-Warraq). Lauzeenaj was made by rolling the filling of sugar and nuts (almonds, walnuts or pistachios) in the sheets of thin dough to create a long roll. These were cut into smaller pieces and drenched in almond or walnut oil and sugar syrup. The waraq, or thin dough was made not by rolling the dough out but by making a batter and pouring it onto a hot griddle. Although the diamond shaped baklava is the most common form, these circular types are still popular today. Although no ancient Persian cookbook survives, the fact the Persian aj suffix is used in the word lauzeenaj is an indication of an earlier Persian development.
The nomadic Turkish technique of making thin bread may have been incorporated by the Ottoman Turks to make delicate layered baklava. Or perhaps the waraq, the thin dough made in Baghdad, was adopted by the Turks, but instead of rolling it, they sandwiched the filling on multiple sheets.
Although Turkish multilayered phyllo baklava has been popularized in many countries, there are still some regions that make it differently. Charles Perry speculates that Azeri baklava is a more ancient form because it has only eight layers. I have a Persian cookbook which calls for only four and Farida (Farida’s Azerbaijani Cookbook blog) makes hers with just three layers. He says that the Azeri baklava “seems to combine the Iranian tradition of pastries with nut filling baked in ovens with the layered bread of the Turks.” Did the nomadic Turks introduce the layering technique? I am not sure if the answer is so simple.
Source: Delights from the Garden of Eden, Nawal Nasrallah
A Taste of Thyme, Edited by Sami Zubaida and Richard Tapper