Which landlocked Southern African country, known for its diamond wealth and unique Okavango Delta, achieved independence in 1966 and boasts a stable democratic government?

1. Its economy is heavily reliant on mining, especially diamonds.
2. The Okavango Delta, a vast inland river delta, is one of its major tourist attractions.
3. It shares a border with South Africa, Namibia, Zambia, and Zimbabwe.
4. The Kalahari Desert covers a large portion of its territory.