In de tweede helft van de 17e eeuw bevonden zich vele groepen van inlandse krijgers van overal uit de Indische archipel op het eiland Java, die zich verhuurden aan de machtigste vorsten of zelfs aan de VOC, om controle te krijgen over bepaalde gebieden en handel. Deze krijgers waren vaak religieus geïnspireerd of namen een voorbeeld aan heroïsche helden. Hoe dan ook was hun militaire inzet van een hoog niveau en werden ook naast slag- en steekwapens de moderne Europese vuurwapens in de strijd ingezet. Met het Europese kolonialisme van de 19e en begin 20e eeuw werd langzaamaan vergeten dat deze formidabele krijgergroepen er ooit waren geweest, zoals dhr. Kemper beschrijft in zijn studie War-bands on Java.

In zijn introductie schijft Kemper: "What is war to whom? The troops roaming on Java in the late seventeenth century were of all shapes and colours. Some came from Sulawesi, some from Madura; some were religious others acquisitive. Usually they operated in small units known as war-bands led by a warlord. Despite the differences between these war-bands, many of them did gather and fight under a single banner. Often they hurdled behind overlords -sunans or sultans- who were in need for additional brawn; a competitive market of martial supply and demand resulted. The king with the most men usually won.

Even the Dutch East India Company (VOC) was part of this market and relied on indigenous patrol. In 1677, the Company decided to support the Central Javanese realm called Mataram and thus landed in a diplomatic struggle for troops. This thesis wonders how VOC men reported on these warriors and what clues are given of a Javanese military labour market at odds with the European one. The Dutch commanders would soon find out drawing in allies was as important as winning battles; the extent to which they could enter the networks of warlords and rulers thereby determined much of their victory. This thesis tells how far they did in the two chaotic and bloody years of 1677 and 1678."

In 2014 schreef dhr. S.C. Kemper zijn masterscriptie (Universiteit van Leiden), getiteld War-bands on Java: military labour markets described in VOC sources.