I recently purchased the book Manners and Customs of Bible Times by Ralph Gower and am already, within the first few pages, finding it to be of value in gaining a fuller understanding of the Bible.
In the first chapter we learn about clothing. Typical clothing for an average Bible character consisted of a loincloth, maybe, and then a tunic (or coat) which was basically just a long t-shirt, and for the more wealthy or in cold-weather, a cloak (or mantle) which was basically an oversized robe.
A typical poor person might have nothing more than the clothes on his back, and his cloak was the only protection he had from the weather. The cloak was sometimes given as a guarantee for a loan, but the cloak had to be returned to the owner every night as it was the only bed-cover a person might have. Accordingly, a Jewish law court might award a person's tunic in a lawsuit, but never his cloak. Clothing was so valuable that Jewish law stipulated a list of clothing that could be rescued from a burning structure even on the Sabbath when work was strictly forbidden. For John the Baptist to tell his disciples to give away any spare coats was a revolutionary thought.