The Origins of Bhangra : The word "Bhangra" (pr. BONN-gruh) originally referred to a harvest dance performed in the Punjab region of what is now India. Bhangra is believed to date back to the 14th or 15th century, though it may be even older, and eventually referred not only to the dance itself, but also the music, characterized by the intense beating of a drum called a dhol.
Modern Bhangra: In the 1970s and 1980s, Bhangra became modernized, primarily by Punjabi expatriates living in the United Kingdom. Elements of hip-hop and electronica were fused with the beating of the dhol and other traditional instruments.
The Success of Bhangra Music: Bhangra provides a sense of identity to many Punjabi (and other Indian) youth around the world, but has a particular stronghold in England. It's a logical success - the music is hip, pulsating and danceable, but provides linguistic and historical ties to their traditional culture. Many non-Punjabi people are also catching on to the sounds of bhangra, as it's frequently used in film soundtracks and has even made forays into American hip-hop - Missy Elliott's "Get Ur Freak On" is backed by a bhangra track, for example.
Bhangra Starter CDs: Bhangra CDs can be a bit tricky to find in the US, as they're primarily imports and only sold to very niche markets - your best bet is, if you live in a big city, to find an Indian food or gift store, as they will likely have a few bhangra CDs in stock. Luckily, Rough Guides has put out a couple of great and highly available compilations that will get you started on your search. I prefer the original "Bhangra" CD, but "Bhangra Dance" - slightly more modern - is also fantastic.
