Late Middle Ages
The Ship of Fools, by Hieronymus Bosch (about 1490 AD)
In the Late Middle Ages, the Mongol Empire brought peace to most of Asia, and encouraged trade along the Silk Road. Poland, Russia, and Italy profited from this trade. By the early 1300s, however, Europe suffered from both war and disease. England and France began to fight the Hundred Years' War, which made both England and France much poorer. Germany and Italy fought a long series of wars as well. The wars were made much worse by the Black Death, or bubonic plague, which spread along the Silk Road from China to Europe starting in 1328, killing millions of people and causing the collapse of the Mongol Empire.
By the 1400s, after the plague, Europe looked very different. The wars were over. The end of the Silk Road forced traders to look for other ways to get things from China and India. Explorers began to try to find a way to sail from Europe around Africa to China. In 1453, the Ottomans conquered the last traces of the Roman Empire in Constantinople. In 1492, Spain forced the last Muslim rulers out of Granada (and the Jews). Instead of Europeans depending on the Eastern Roman Empire and West Asia and Central Asia, now they were trying to grow on their own.
To find out more about medieval history, check out these books from your local library or from Amazon:
The Holy Roman Empire and Charlemagne in World History, by Jeff Sypeck (1997). An exciting and accurate account of the formation of one of Europe's great empires.
Beyond the Myth: The Story of Joan of Arc , by Polly Brooks (1999). Accurate and thoughtful, with good illustrations and maps, though more a biography than a history.
Constantinople: The Forgotten Empire, by Isaac Asimov (1967). This book got many future Byzantinists started on their path. It's out of print, but you can get it used.
A Little History of the World, by E. H. Gombrich (2003). Written in 1935, the history is a little out of date, of course, but it is written to convey the facts of all of human history to young people, and I think it does a good job.