As mostly did Hellenic-derived philosophy from the third to the sixteenth centuries CE (if not more) in Christian, Jewish and Muslim contexts alike, yet nobody seriously says that it is not philosophy, or that it does not use a rational method. I am also not sure of how "secular" Ancient Chinese thought can be said to be, in comparison with Indian speculation. Chinese thought in its earliest phases tends to focus on ethics, while in India the focus appears to me epistemological (and arguably, ontological in Ancient Greece, but this is oversemplification anyway).@Thanksforallthefish mentioned these schools too, but the point is not that they were being inexistant, but that they didn't really made it as the norm of Indian philosophy, which remained dominated by religious or, rather, semi-religious concerns. It doesn't mean they weren't practical of course, just that it never went to the same way than Greece or China.
Then, there's the problem that we know relatively little of the presumable wealth of Chinese speculation in the Warring States period (a lot went lost when Daoism and Confucianism came to frame the system), while most Indian stuff we possess that can be securely dated is from a much later period.
However, the Nyaya school in India (which was certainly nothing like minor or marginal) and the Aristotelian one in Greece developed theories of logical reasoning to reach truth about the world rationally. These are presumably independent, or almost independent, developments, and I am not aware of surviving ancient Chinese texts showing something comparable.