Sanibel and Captiva became one island about 6,000 years ago, and the first known humans in the area were the Calusa people, who arrived about 2,500 years ago. This island is often called a “barrier island sanctuary” by those who live there. The city incorporates the entire island, with most of the main city area at the east end of the island. With easy causeway access, Sanibel is a popular tourist destination known for its shell beaches and wildlife refuges, which make up more than half of the island. The Island also hosts the Sanibel Historical Village and a variety of other museums and theaters, in addition to many non-profit organizations like the Sanibel-Captiva Conservation Foundation, the Clinic for the Rehabilitation of Wildlife, and the Sanibel Sea School.