Food supplies coming from the Yangtze region had been unable to travel through it since it had been silted through the years .
The Yangtze region had been traveling through Bian River -- a canal that connected the Huai River and Yellow River -- prior to the Anshi Rebellion .
Food supplies coming from the Yangtze region , which had been traveling through Bian River -- a canal that connected the Huai River and Yellow River -- prior to the Anshi Rebellion , had been unable to travel through it since it had been silted through the years .