The land of Azerbaijan and its people are divided into two parts. One, extending north of the Araxes River in the geographical region of Transcaucasia, is today an independent state. The Republic of Azerbaijan covers 33,436 square miles (86,600 sq km) and includes the Nagorno-Karabagh Autonomous Oblast (NKAO) in the west (1,699 square miles or 4,400 sq km), as well as the noncontiguous Nakhichevan Autonomous State in the southwest (2,124 square miles or 5,500 sq km). The republic borders Russia in the north, Georgia in the northwest, Armenia in the southwest, Iran in the south, and the Caspian Sea in the east. The other part of Azerbaijan, south of the Araxes River, lies within the frontiers of Iran, and is known as Iranian Azerbaijan. The people on both sides of the border speak the same Azeri Turkish language, share the religion of Islam, and had a common history until the Russian conquest of northern Azerbaijan in the first half of the 19th century.

Nearly half of the Azerbaijani Republic's territory is covered by mountains, of which the highest is Bazarduizi Peak at 14,652 feet (4,466 m). The three main relief features of Transcaucasia converge within the country. These are the Greater Caucasus Mountains in the northeast, the Lesser Caucasus in the southwest, and the Kura River depression between them. In the extreme southeast are the Talysh Mountains, and the Araxes River stretches between the Zangezur and Dilagarez mountain ranges. The highest elevations are in the Greater Caucasus region, which abounds in glaciers and rapids. The middle-altitude ranges are broken by deep valleys. The Greater Caucasus drops off abruptly to the east and becomes arid hills. North of this range, in eastern Azerbaijan, extends the sloping Kusary Plateau. The lowest part of the country, the Kura River depression in the southeast, is divided into two sections. Its western area and northern rim are marked by hills, ridges, and valleys. The central and eastern areas of the depression consist of alluvial flatland and the low delta of the Kura River along the coast. The 500-mile-long Caspian coastline has few irregularities. The largest projections are the Apsheron Peninsula, the Sara Peninsula, and the Kura Sandbar. The major waterways are the Araxes and Kura rivers. The rainfall averages 200-400 mm per year. In the south of the Azerbaijani Republic a subtropical climate prevails, and rainfall is sufficient for agriculture. Eighteen percent of the land is under cultivation, and 24 percent is pasture. Near the capital city of Baku lie extensive oil and gas deposits. The production of electrical energy averages about 3,250 kwh per capita. The rail lines total 1,296 miles (2,090 km) and highways 22,753 miles (36,699 km).

Azerbaijan's capital, Baku, is situated on the Apsheron Peninsula and is the largest city of the republic, containing about 25 percent of the country's population. It is a major Caspian Sea port and a center of the oil industry. The republic's second-largest city is Ganja, 198 miles (320 km) west of Baku. 

Iranian Azerbaijan lies between the Caspian Sea coast, Lake Urmia, and the Araxes River. A part of the Islamic Republic of Iran, a majority of its population is Azeris, whose numbers in Iran are estimated at 15 million. Major cities in Iranian Azerbaijan are Tabriz, Ardabil, Zanjan, Khoi, and Maragin. The largest of them, Tabriz, is an important industrial center with a population of over 600,000.

The Azerbaijani Republic's population, including Nagorno-Karabagh, exceeds 7.5 million, of which about 85 percent are ethnic Azeris. The two largest non-Azeri groups in 1989 were Russians, 392,000 or 5.8 percent, and a similar number of Armenians.