Neo-Confucianism emerged in China during the Song dynasty (960-1279 CE) as a response to the growing influence of Buddhism and Taoism on traditional Confucian teachings. It sought to synthesize the ideas of these three philosophies into a cohesive belief system that could guide individuals towards personal and social harmony.

The main principles of Neo-Confucianism can be summarized as follows:

1. The Unity of Heaven, Earth, and Humans: Neo-Confucianism emphasizes the interconnectedness of all beings and the harmony that exists between the natural world and human society. This principle is rooted in the Confucian belief that humans are a microcosm of the universe and should strive to align their actions with the natural order.

2. The Principle of Humaneness (Ren): Ren, or humaneness, is considered the highest virtue in Neo-Confucianism. It encompasses qualities such as benevolence, compassion, and righteousness, and is seen as the key to achieving harmony within oneself and with others.

3. The Principle of Righteousness (Yi): Yi, or righteousness, is closely linked to Ren and is seen as the moral principle that guides one's actions. It involves acting with integrity, fulfilling one's duties and responsibilities, and upholding moral values.

4. The Cultivation of the Self: Neo-Confucianism places a strong emphasis on self-cultivation and self-improvement. This involves developing one's moral character, cultivating virtues, and seeking knowledge and wisdom.

5. The Doctrine of the Mean: The Doctrine of the Mean, derived from the teachings of Confucius and Mencius, emphasizes the importance of moderation and balance in all aspects of life. It encourages individuals to find a middle ground between extremes and to avoid excess and deficiency.

6. The Importance of Ritual and Ceremony: In Neo-Confucianism, ritual and ceremony are seen as important tools for cultivating virtues and maintaining social order. They also serve as a means of expressing respect and gratitude towards ancestors and the natural world.

7. The Role of Education: Education is viewed as a crucial means of self-cultivation and societal improvement in Neo-Confucianism. It is seen as a lifelong process that involves not only the acquisition of knowledge but also the development of moral character.

In conclusion, Neo-Confucianism is a complex and multifaceted philosophy that sought to reconcile the teachings of Confucianism, Taoism, and Buddhism. Its main principles revolve around the unity of all beings, the cultivation of virtues, the pursuit of balance and harmony, and the importance of education and ritual. These principles continue to influence East Asian societies to this day, making Neo-Confucianism a lasting and significant legacy of Chinese culture.