What were the Hundred schools of Chinese philosophy, and what is the relation to Mao Zedong?

The Hundred Schools of Thought were philosophers and schools that had flourished from 770 to 221 BC, an era of great cultural and intellectual expansion in China. Even though this period, known in its earlier part as the Spring and Autumn period and the Warring States period in its latter part, was wrought with chaos and bloody battles, it is also known as the Golden Age of Chinese philosophy because various thoughts and ideas were developed and discussed freely. This phenomenon has been called the Contention of a Hundred Schools of Thought.

https://en.wikipedia.org/wiki/Hundred_Schools_of_Thought

In modern times, events surrounding the May Fourth movement in 1919 seemed likely to lead to the Chinese acceptance of Western ideological influences... the final result of the May Fourth uprising, was not the realization of democratic reform but the founding of the Chinese Communist Party in 1921. The widespread assumption that Marxism has effectively westernized Chinese philosophical culture is seriously challenged by Mao’s own claim, upon adopting Marxist ideology, that he was using a Western heresy to confront the West (see Marxism, Chinese)...

https://www.cambridge.org/core/journals/china-quarterly/article/abs/chinese-communist-treatment-of-the-thinkers-of-the-hundred-schools-period/A14332EC9C7C2E583F95C2EDEAAB903B

Hundred Schools of Thought

In the turbulent Spring and Autumn Period (770-476BC) and Warring States Period (475-221BC), many schools of thought were flourishing. The four most influential schools of thought that evolved during this period were Confucianism, Taoism, Mohism, and Legalism. There were also other schools like Yin & Yang, Eclectics, Logicians, Coalition persuaders and Militarism. The hundred schools of thought showed the fierce political and class struggles for survival among regional wars between the rising landed class and slaveholder class. The flouring thoughts intensified activities and debates in the intellectual and ideology system in ancient China and exerted great influence on Chinese culture.

http://en.chinaculture.org/library/2008-02/07/content_23009.htm

I think there is also a link to Mao's Hundred Flowers Campaign:

The Hundred Flowers Campaign, also termed the Hundred Flowers Movement, is the period referring to a brief interlude in the People's Republic of China from 1956 to 1957 during which the Chinese Communist Party (CCP) authorities encouraged a variety of views and solutions to national policy issues, launched under the slogan: "Let a hundred flowers bloom, let the hundred schools of thought contend."

It is thought by some scholars, such as Jung Chang, that the campaign was a political trap, alleging that Mao persecuted those who had views different from the party. The ideological crackdown following the campaign's failure re-imposed Maoist orthodoxy in public expression.

https://en.wikipedia.org/wiki/Hundred_Flowers_Campaign