The number of rhinos poached exploded in 2008 and has grown exponentially ever since with estimates suggesting that in South Africa this year over 800 animals will be killed for their horns.
The use of rhino horn in traditional medicines is a fad for the nouveau riche in Vietnam and it is thought that the booming Vietnamese economy has caused the current mass poaching.
Vietnam was the traditional market but during the Vietnam war and subsequent two decades of rebuilding the traders had to look elsewhere to richer markets such as Japan, South Korea, Taiwan, Hong Kong and China. However trade bans closed these markets and the number of rhinos poached was kept to a minimum.
Rhino horn is thought to be a tonic after excessive drinking and and also an aphrodisiac but there is not scientific proof of either.
The booming market was also fueled by a rumour that a Vietnamese politician had been cured of cancer through traditional medicine utilising ground rhino horn. The politician, if there ever was one, was never identified. Regardless there is no scientific evidence for its use as a cancer cure.
Source: http://www.thestar.com/news/world/2013/07/05/fighting_a_booming_trade_in_rhino_horns.html