(Photo retrieved from fightforrhinos.com)
The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) banned the international trade of rhinoceros horn in 1977, and there was a decline in poaching through the 1990s, especially for the black rhino population. In South Africa, between 1990 and 2007, there had not been more than 36 rhinos poached in any single year. In 2008, there were 83 rhinos killed by poachers. The number continued to rise annually with a reported 668 rhino killed in 2012. More than half of the rhinos killed in 2012 were in South Africa’s Kruger National Park, which shares a border with Mozambique and Zimbabwe (Orenstein, 2013, p. 86).
Poaching in South Africa has more than doubled each year over the past five years. The CITES ban on the trade of rhino horn is no longer working because of the growing demand of rhino horn in recent years (Biggs, 2013, p. 1038).
(Retrieved from http://www.savetherhino.org/rhino_info/poaching_statistics)
More recently, Vietnam has become a new market for rhinoceros horn. There, it is considered to be a cure for a hangover, an aphrodisiac, and a cure for cancer. However, there is no convincing research to show that rhino horn has any of the medicinal benefits that are attributed to it.
Commodity Chain for Illegal Rhino Horn Trade
Poachers kill rhino and remove horn -> Horn is transported to Mozambique by truck -> Horn is transported by plane out of Africa -> Horn arrives in Vietnam to be sold to a medicine shop -> medicine shop owner prepares horn for sale -> Consumer purchases rhino horn
This entire process can be completed in 24 hours.
(While illegal rhino horn is traded in many Asian countries, and some other parts of the world, my information is focused on the South Africa to Vietnam commodity chain)