Southern Yunnan is in China.
Lao Airlines  flies from Wattay International Airport (IATA: JHG, ICAO: ZPJH) to Xishuangbanna Gasa Airport (IATA: JHG, ICAO: ZPJH) twice a week (Fridays and Sundays).
Trekking in southern Xishuangbanna. There are a number of cafes in Jinghong where you can meet up with guides who will take you on treks to see old Dai and Bulan villages in Southern Yunnan. Cost varies, but plan on about ¥300 per person for a four day trek.
The treks are pretty easy, since you will be staying in villager's homes every night along the trail. There's no need to camp, and the terrain you'll be hiking over is hilly, but not mountainous.
Xishuangbanna is home to some of the rarest plant species and wildlife. Here you can experience the real village life of the Dai ethnic minorities, by visiting the villages you can learn about the Dai culture and get to know their daily life routines. If you happen to visit Xishuangbanna in April then you have made it just in time for the Water Splashing Festival where you can join in on one of the most important celebratory days of the Dai ethnic group. 
For a astounding exotic experience you must see the Wild Elephant Valley that is part of the Menyang Reserve. You can see the elephants in their natural habitats and enjoy the magnificent scenery of the great outdoors from the different viewing platforms in the reserves or even from some of the tree houses. Apart from elephants in the reserve there are also other wildlife you can spot in the park. You can also check out the exciting elephant performance in the reserve where the elephants are colorfully decorated and are led by the keepers and perform some of the most stunning routines.