Conversation so far:
What is the south-point chariot?
The south-pointing chariot was another mechanical device credited to Zhang Heng.
Are there any other interesting aspects about this article?
It was a non-magnetic compass vehicle in the form of a two-wheeled chariot.
When was it created?
125.
Did any one aid him on its construction?
Whether Zhang Heng invented it or not, Ma Jun (200-265) succeeded in creating the chariot in the following century.
Was there anything else he created?
inventing the first odometer.

Question: When was this invented?
Self-contained rewrite: When was the first odometer invented?