Okay, imagine a big group of people who lived a long time ago, called Muslims. They lived in a place called the Islamic world, which was in the Middle East, parts of Asia, and North Africa.
These Muslims were very smart and had lots of ideas about things like math, science, and art. They came up with new ways of doing things that helped people all over the world, including in Europe during the medieval times.
One of the biggest things they did was they kept a lot of books and wrote down lots of information about different subjects. They even translated books from other languages, like Greek, into Arabic so that people who spoke Arabic could read them.
In math, they came up with a concept called algebra which helps solve really hard math problems. They also made big advances in geometry, like figuring out the angles of a triangle.
In science, they built some pretty impressive things like hospitals, libraries, and centers of learning called madrasas. They also studied the stars and planets and made star charts to help people navigate the seas. They also learned how to make medicine and new medical treatments.
In art, they made intricate designs and patterns that were used in things like pottery, textiles, and buildings. They even made beautiful calligraphy, which is fancy writing that looks like art.
So, the Islamic world had a lot of smart and creative people that came up with many new ideas and inventions that helped people all over the world, including Europe during the medieval times.