Ancient Britain refers to the period before the arrival of the Romans in 43 AD. During this time, the land was inhabited by various tribes, including the Celts, who lived in small communities and practiced farming, hunting, and gathering. They built hill forts and used simple tools made from stone and wood. The arrival of the Romans marked a significant change in Ancient Britain. They introduced new technologies, such as roads and buildings, and established towns like Londinium (modern-day London). The Romans also brought their culture, including baths and amphitheaters, which influenced the local way of life for centuries.