The history of Liverpool can be traced back to 1190 when the place was known as 'Lo', possibly meaning a pool or creek with muddy water, though other origins of the name have been suggested. The borough was founded by royal charter in 1207 by King John, made up of only seven streets in the shape of the letter 'H'. Liverpool remained a small settlement until its trade with Ireland and coastal parts of England and Wales was overtaken by trade with Africa and the West Indies, which included the slave trade. The world's first commercial wet dock was opened in 1715 and Liverpool's expansion to become a major city continued over the next two centuries.