The history of Panama is very political in nature, largely due to the international nature of its initial colonization (everyone from the Spanish to the Scots,) use as source of raw material and labor for Europe, to its canal-building attemps from France and the U.S.
As always, check your local library; as much as I love the internet, it is not going to list the wonderful books published decades ago on the subject--the coolest book I've come across was a photographic history of the canal building project published in 1933 that I bought for my mother as a Christmas gift. Should you need to use the 'net, find your local library's site and execute a search there...
Next stop, Amazon:
Amazon.com: History of Panama - Amazon.com: Books
Cheers.