Xylography is often referred to as block printing or woodblock printing, and the truth is that there really isn’t a difference between any of them.
Just like block printing, xylography is a technique for printing that uses a carved relief, that when inked will show the uncarved parts in black (or whatever color the ink is) and the carved parts as white space.
Xylography originated as a technique in Japan during the third century, and spread from there. It became wildly popular for printing documents and designs on textiles, although the use for document printing faded out over time. However, many people all over the world still use xylography techniques for crafts, art pieces and even designs for clothing.
Many would say that the technique remains most used in India, although some cultures still have strong roots in it. What is neat about the technique is that anybody can get started with it, as the materials needed are very inexpensive and easy to find.
Portuguese culture tinged with medieval traces was imported to Brazil and here it developed into the string literature. Most of Brazilian xylographers, especially the northeastern ones, are influenced by the string literature.