Final answer:
The ideology of complete self-control and harmony with the cosmos during the third period of Buddhist development led to the evolution of Mahayana Buddhism. It expanded the path of enlightenment, gave rise to branches like Chan and Pure Land Buddhism, and later influenced the emergence of Vajrayana Buddhism.
Step-by-step explanation:
Throughout the third period of Buddhist development, the ideology that idealized complete control over oneself in order to be in harmony with the cosmos led to the formation of Mahayana Buddhism. This branch of Buddhism emphasized the potential for universal salvation and compassion, extending the path toward enlightenment to all sentient beings, not only monks and ascetics. Mahayana Buddhism introduced new scriptures and concepts such as the Bodhisattva path, where an individual delays personal nirvana to assist others in reaching enlightenment.
Additionally, sects like Chan Buddhism (known as Zen in Japan) and Pure Land Buddhism became popular during this time. Chan Buddhism focused on meditation and direct understanding through practice rather than scholarly study, whereas Pure Land Buddhism stressed devotion to the Amitabha Buddha and the recitation of his name as a means to rebirth in the Pure Land, a realm free from suffering.
The third period also saw the emergence of Vajrayana Buddhism or Tantric Buddhism, which incorporates complex rituals and the use of mantras and mandalas to realize enlightenment swiftly.