How did Chinese mathematics decline between the 14th and 16th centuries?

Between the 14th and 16th centuries, Chinese mathematics experienced a significant decline, characterized by the loss of advanced knowledge achieved during the Song-Yuan period. By the 16th century, sophisticated techniques such as the "method of the celestial unknown" were no longer understood, and they were largely forgotten by the 17th century.1

Several factors contributed to this decline:

• Loss of Counting Tools: The traditional use of rods as a counting tool ceased, which likely rendered the complex algebraic place-value notations of earlier eras unintelligible.1
• Shift in Focus: There was a rapid diffusion and prioritization of the abacus, which became the primary focus of mathematical literature, such as Cheng Dawei’s 1592 Suanfa tongzong ("Systematic Treatise on Mathematics").1
• Textual Gaps: While some major 13th-century works were preserved in encyclopedias like the Yongle dadian, commentaries written by the end of the 15th century indicate that these texts were no longer being comprehended by scholars.2

By the time European missionaries arrived in the late 16th century, there was a notable disconnect between contemporary scholars and their own mathematical heritage, necessitating a later period of rediscovery and synthesis with Western algebra.1