Signs and billboards here have abandoned the Cyrillic script of Russians in favor of the Latin alphabet of the Turks, whose language is a very close cousin to Azerbaijani. Turkish businesses and Turkish construction crews are everywhere here.
But the closest family ties here are to the millions of Azeris across the border in Iran.
We board an aging bus early on a Saturday morning in Baku for what will prove to be a 20-hour ride to Tehran. The fare: $11. Most of our fellow riders are women carrying a duffel-bag or two full of goods that were cheaper in Azerbaijan than in Iran. One is a former teacher, an Azeri who lived in Armenia until after war broke out between the two countries in the late 1980s. Now he is a watchman at a parking lot in Baku, making the trip to Tehran to research a book on Azeri poetry in Iranian library collections.
Through a lot of fumes and vibration in the back of the bus, the desert emptiness of southern Azerbaijan is eventually crowded by sharp, leafy mountains, steep-terraced fields, limestone houses with rich gardens behind rock walls to keep out the napping cows.
As we approach the Iranian border, long lines of trucks are parked along a Caspian beach, waiting for the Azerbaijani customs officials to finish lunch. We finally pull into a large garage where the bus is emptied and all the baggage searched. The border guards - surprised to see Americans - tell us this is an internal border. Only Iranians and Azerbaijanis can cross it. This is unknown to the foreign ministries of either country, but no matter. We are escorted to the office of the commandant, who decides to call the head of the Azerbaijani Border Guard in the capital, who finally decides to give his personal permission for us to cross the border.
Another 20 minutes of fussing over our visa stamps passes before we grab our bags and reboard the waiting bus. The women on board have been transformed. They now wear scarves tied under their chins, covering their hair, and their skirts and short-sleeved blouses are covered in loose black robes, as Iranian law requires. Some complain of the sticky heat.
Just before we cross a bridge into Iran, another young Azeri soldier boards for a last check. He immediately singles us out. "How do I know these stamps are real?" he asks, glaring at the stamps we have just received, 100 yards up the road. Our suggestion that he ask his commanding officer infuriates him.
"Such important people, so many problems," he mutters, and keeps our passports for another 15 minutes before leaving them at the front of the bus and waving it on.
We enter a cleaner and more computerized country - the Islamic Republic of Iran.
In the border city of Astara, young men mob the bus, thrusting Iranian rials by the hundreds of thousands into the windows, desperately seeking dollars.
The Caspian coast here resembles Southeast Asia: people hunched over in rice paddies, and lush mountains popping abruptly out of the flats. As evening falls, shop fronts are open to the street and full of light. Power is cheap. Gasoline costs about 15 cents a gallon. We arrive at our hotel in Tehran after 4 a.m.
Iranian authorities have continually warned us that, though as Americans we should not have any problems from the country's security services, we should be careful.