Java is the most populated Indonesian island. It is possible to cycle quite safely once outside Jakarta. I found it quite bearable in spite of the high density and dangerous driving by buses, trucks. Java has been populated since pre-historical times. It received influences mostly from India before Islam came. This is reflected in most of the ancient monuments. There are several subcultures in Java such as Sundanese, Madurese, etc The geography is punctuated by succesive volcanoes separated by valleys where the population lives and farms.