Wikipedia says:

Palm sugar is made by making several slits into the bud of a coconut tree and collecting the sap. Then, the sap is boiled until it thickens after which, in the traditional way, it is poured into bamboo tubes between 3-5 inches in length, and left to solidify to form cylindrical cake blocks. Alternatively, it can be poured into glass jars or plastic bags
Looks like it's alright, but even I know we can't always trust Wikipedia