History, and the teaching of Buddha:
In India, women were treated very poorly in the Buddha's time. Women were second class citizens and were even expected to throw themselves onto the funeral pyres of their husbands. Girl babies were considered to be a punishment while male babies were a blessing.
The Buddha's teachings clearing differed from his comtemporary teachings because he when one of his followers, King Pasenadi of Kosala, came to him, lamenting the birth of a daughter, the Buddha reassured him that good daughters were as good as good sons. Also, Buddha allowed both men and women to join religious orders and said that both genders could achieve enlightenment, however, there was some controversey over this. He was at first unwilling to allow women into the order be a number of reasons. He felt that if he were to go against the social norms of his times so drastically, his teachings may carry less weight and would thereby not last and long and reach less people. Also, he believed strongly in the householder olbigations of the female to their families and children. He was eventually persuaded to create and order of nuns, the bhikkhunis, as the counterpart to the monks, the bhikkhunus, where he observed their merit.
Modern Buddhism in the West:
Pema Chodrone is the only female head of a monastery in North America.
Dr. Gotami is an ordained monk
Because western culture is more open to females is leading positions, this is more accepted by practicing buddhist in North America then it tends to be in the east.
Modern Buddhism in the East:
Mae Chee Kyunying Kanitha Wichiencharoen was a Thia Buddhist nun who provided shelter to tens of thousands of battered women and childen and is recognized as a key figure in Buddhism
Khun Mae Dr. Siri Krinchai is a prominent meditaranian master
The order of nuns in the east was recently reestablished. This was a difficult task because the ordination of new nuns called for a current nun to present and since the bhikkunis had died out, this was not possible. But they managed to get a nun from a slightly different order to oversee the ritual. Also a monk must be present.