Archaeologists have found a massive ancient fortification enclosing the Khaybar Oasis in the North Arabian Desert. It is one of the two largest fortifications in Saudi Arabia.Oases in the region have been settled by human populations for 4,000–5,000 years. An oasis is a small patch of vegetation in the desert. Fed by sources of freshwater such as underground rivers and high water tables mean these areas can become vibrant, lush sanctuaries for plant and animal life.Human-built aquifers and channels can help irrigate these areas making them suitable for long-term settlement...Fortifications at Khaybar once stretched for 14.5 km and were between...