Passage: The Helmand River flows through the mainly desert region of the province, providing water used for irrigation. The Kajaki Dam, which is one of Afghanistan's major reservoirs, is located in the Kajaki district. Helmand is believed to be one of the world's largest opium-producing regions, responsible for around 42% of the world's total production. This is believed to be more than the whole of Burma, which is the second largest producing nation after Afghanistan. The region also produces tobacco, sugar beets, cotton, sesame, wheat, mung beans, maize, nuts, sunflowers, onions, potato, tomato, cauliflower, peanut, apricot, grape, and melon.Since the 2001 War in Afghanistan, Helmand Province has been a hotbed of insurgent activities. It has been considered to be Afghanistan's "most dangerous" province.

Question: What sort of region is the Helmland River flowing through?
desert