Afghanistan: Afghanistan by Jonatahn A. Lee. The books provides a great overview of Afghanistan's rich history from the 15th century to the modern day.

Intelligence: The Secret World: A History of Intelligence by Christopher Andrews. It's a fantastic book that documents the history of intelligence and spy operations throughout human history! Definitely a must read.

China: The Story of China by Michael Wood traces key milestones and developments in China from the Middle Kingdom up until today. It provides an excellent overview of China's history without being dull or dreary.

Iran: America and Iran: A History, 1720 to the Present whose name is self-explanatory. I enjoyed this one as it overcomes the common, but wrong, perception many have that Washington's historic relationship of interaction with Tehran started only after the Islamic Revolution.

African history: I really recommend Martin Meredith. Specifically his books The Fortunes of Africa: A 5000-Year History of Wealth, Greed, and Endeavor and The Fate of Africa: A History of the Continent Since Independence. Toby Green's A Fistfull of Shells similarily takes the reader across West Africa's rich history, from the 15th crntury to the modern day. Also check out David Van Reybrouk's Congo: The Epic History of a People.

Andalusia + Medieval: I cannot recommend Dr. Brian Catlos enough. He is an excellent source on the topic. Definitely check out his books, specifically, Kingdoms of Faith: A New History of Islamic Spain and Infidel Kings and Unholy Warriors: Faith, Power, and Violence in the Age of Crusade and Jihad.

Latin America: Maria Arana's Bolivar: American Liberator is an excellent book on the life of one Latin America's most influential 19th century figures, Simon Bolivar. The book further explores the Bolivarian revolution, its root causes and ultimately Bolivar's downfall.

Ottomans: David Fromkin's A Peace to End All Peace, and The Last Muslim Conquest: The Ottoman Empire and Its Wars in Europe by Gàbor Àgoston. The latter provides an in depth and rich look at the Ottoman Empire's socio-economic and military history from the Empire's rise to the Siege of Vienna and beyond. Why I really loved this book was the author's tying in of pertinent events within the Ottoman Empire to those on Europe, such as the rise of the Hapsburgs. Àgoston also does a great job examining key details within the Empire, such as frontier management, intelligence, diplomacy and military structure!

Arab World: Tim Mackintosh-Smith's Arabs: A 3,000-Year History of Peoples, Tribes and Empires, and Albert Hourani's A History of the Arab Peoples. Al Jabarti's chronicle Napoleon in Egypt transports  the reader to Egypt in the 19th century, and does an excellent job at conveying the Egyptian perspective of Napleon's expedition.

Central Asia: Adeeb Khaled's Central Asia: A New History. The book does an excellent job of explaining the complex history and geopolitics of a region I don't think gets enough attention.

Native American: Bury My Heart at Wounded Knee by Dee Brown, Empire of the Summer Moon by S. C. Gwynne and The Earth is Weeping by Peter Cozzens. National Geographic also had a fantastic visual history book called The Old West by Stephen G. Hyslop. Also check out Blood and Thunder by Hampton Sides.

WW2: Robert Paxton's Vichy France: Old Guard and New Order details the often-overlooked Vichy French government's actions and role in WW2, both within France and the wider Axis. John Gooch's Mussolini's War: Fascist Italy from Triumph to Collapse does an excellent job of looking at the rise of fascism in Italy, and its ultimate demise. The book is really well written, and definitely keeps the reader engaged.

Carthage: Richard Miles' Carthage Must Be Destroyed: The Rise and Fall of an Ancient Civilization. The book is very well written and takes the reader through the origins of Carthage's founding to the peak of it's mercantile empire, and ultimately the Punic wars and the city's destruction. I found it refreshing to read about Carthage from a non-Roman perspective. Definitely check it out!

Visual History: DK Publishing's book on the US Civil War. The mix of visual and text reading really helps things settle in. Also check out their books on WW1, WW2, The History of the World Map by Map and WW2 Map by Map.