peoples had mastered the technique of horseback warfare and were far
ahead of the Chinese, although the Chinese imitated their methods. The
peasants of China, as they penetrated farther and farther north, had to
be protected by their rulers against the northern peoples, and since the
rulers needed their armed forces for their struggles within China, a
beginning was made with the building of frontier walls, to prevent
sudden raids of the northern peoples against the peasant settlements.
Thus came into existence the early forms of the "Great Wall of China".
This provided for the first time a visible frontier between Chinese and
non-Chinese. Along this frontier, just as by the walls of towns, great
markets were held at which Chinese peasants bartered their produce to
non-Chinese nomads. Both partners in this trade became accustomed to it
and drew very substantial profits from it. We even know the names of
several great horse-dealers who bought horses from the nomads and sold
them within China.

3 _Cultural changes_

Together with the economic and social changes in this period, there came
cultural changes. New ideas sprang up in exuberance, as would seem
entirely natural, because in times of change and crisis men always come
forward to offer solutions for pressing problems. We shall refer here
only briefly to the principal philosophers of the period.

Mencius (_c_. 372-289 B.C.) and Hsün Tz[)u] (_c_. 298-238 B.C.) were
both followers of Confucianism. Both belonged to the so-called
"scholars", and both lived in the present Shantung, that is to say, in
eastern China. Both elaborated the ideas of Confucius, but neither of
them achieved personal success. Mencius (Meng Tz[)u]) recognized that
the removal of the ruling house of the Chou no longer presented any