You should be talking about the soundtrack "Stealing Power"

"Stealing Power" is the original soundtrack of the Hong Kong movie "Tai Chi Zhang Sanfeng". It was composed by Hong Kong's outstanding film soundtrack master Wu Weili. " "Qin and Xiao Ensemble" is his original creation. In the song, the erhu appears vigorous and powerful amidst the powerful sounds of the pipa and drums, vividly embodying the light and shadow of the sword. It also often appears in Hong Kong and Taiwan movies and TV series such as "Once Upon a Time", "Fang Shiyu", "Nine Levels of Sesame Official", and "Lover's Bodyguard".

You can search "Stealing Power" Tai Chi Zhang Sanfeng Baidu MP3 on Baidu

I only saw your question when I was reviewing this TV series. I hope it will be helpful to you

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