Early Chinese philosophical system, first developed during the Warring States Period of the Eastern Zhou Dynasty, around 500 B.C.E, and named after its founder, Mo Tzu. Mohism is sometimes described as primitive communism, which is not entirely innacurate, but is probably an oversimplified view. Mohism was first and foremost a reaction against contemporary beliefs and practices, particularly Confucianism and the dominant Legalist doctrine.
Mohism was founded on the premise that human nature was fundamentally good, and all people should love each other universally. Moh Tzu was particularly firm in his rejection of the idea of filial piety, which he felt was innapropriate because it implied that one's highest loyalty was owed to one's family, rather than to everybody equally. He also rejected the the traditional emphasis on ritual and formality, which he felt were distracting, and brought no real benefits; he was particularly firm in his rejection of the three year mourning period for one's parents which was prevalent at the time, which he felt served no purpose except to draw healthy and productive individuals away from society to nobody's benefit except the dead.
Mohism is also one of the earliest recorded pacifist philosophies, rejecting all forms of aggressive war, and holding that the only situation in which warfare was acceptable was in self-defense. It also maintained a rationalist attitude towards government, rejecting the prevaling idea of the Mandate of Heaven, in favor of the idea that the king was simply a man, who should be obeyed only as long as his actions were in accord with justice and the common good. On a note which most moderns would find a bit less sympathetic, Moh Tzu was strident in his attacks against music, which he felt was an occasion for extravagance and a waste of resources which might be better spent on helping the needy.
Mohism was eventually wiped out with the ascencion of Qin Shi Huang Di to Emperor, who followed the Legalist doctrine and was aggressive in his attacks on other philosophies. Elements of its philosophical view survived in some aspects of Taoism's social idealism, and it had a lasting effect on the development of Confucianism, which became particularly concerned around the time of Mencius with reacting to and formulating arguments against Mohist doctrine.