Crusaders brought back chess from the Islamic world.
Crusaders brought back chess from the Islamic world.

The Crusades lasted 174 years, but according to History Learning Site, only 24 of those years actually involved fighting. Trading was a much more common activity throughout the various campaigns. Numerous objects and ideas passed from Muslims to Christians and vice versa.

Food

The Crusaders discovered a multitude of new things to eat in Muslim regions. Many of them returned home with exotic food items like sugar, coffee, sherbet, dates, apricots, lemons, sugar, ginger, melons, rhubarb and even rice. The Crusaders often had to buy their own food during campaigns, as discussed by Angeliki E. Laiou in "Byzantine Trade with Christians and Muslims and the Crusades." Therefore, it is not surprising that they encountered and brought these foods back home with them.

Tools and Household Items

In spite of the embargoes described by NTLWorld on trade between Christians and Muslims, Crusaders often exchanged textiles from the West, such as linen and wool, with the Muslims they met in the East. They received a plethora of useful items in return. For example, writing paper, mattresses and wheelbarrows moved West with the Crusaders. Other objects received from the Muslims include mirrors, carpets, cotton cloth, ships compasses, water wheels and shawls. Thus, it appears that the threat of excommunication for trading with Muslims had little effect on the Crusaders.

Ideas

Some trading took place on a cultural level. Algebra and chemistry were carried from East to West, as were the Arabic numerals 0 through 9 and the game of chess. Other ideas adopted by Christians from Muslims were irrigation techniques and the use of painkillers.

Harmful ideas also proliferated through trade. In "The Crusades and Islam," professor Norman Housley notes that "two of the most fervent supporters of a crusade to recover the Holy Land in the late Middle Ages, Marino Sanudo Torsello in the early fourteenth century and Emmanuele Piloti in the early fifteenth century ... derived their expert insights into the enemy's situation from their own trading experience."

Architecture

Castles already existed in both the West and the East at the time of the Crusades. However, the Muslims had applied advanced science to their construction design, using the land surrounding the castle for maximum benefit, as History Learning Site explains. ArchNet details how the flow of architectural ideas was not one-directional: "it is difficult to assess the relative effects which Crusader, Byzantine and Islamic architecture had on each other." But it is clear that they did have a mutual effect. As one example, ArchNet argues that "the Muslim castle at Ajlun is obviously similar to Crusader castles."