Which valley does the twenty-four solar terms originate from?

"Twenty-four solar terms originated in the Yellow River Basin. As early as the Spring and Autumn Period, four solar terms were set, namely, mid-spring, mid-summer, mid-autumn and mid-winter. After continuous improvement and perfection, by the Qin and Han Dynasties, the 24 solar terms had been completely established. In BC 104, the Calendar written by Deng officially listed the 24 solar terms in the calendar and determined their astronomical positions.