Li Yuan meanwhile writes another rebel leader, Li Mi the Duke of Wei, who is near Luoyang, trying to see if Li Mi would be willing to follow him.

Li Mi declines, insisting on his own destiny to lead.

He is pleased with Li Yuan's response, believing that Li Yuan is willing to support him, and from this point on, Li Mi and Li Yuan often exchange messengers.

Li Yuan's campaign against Chang'an thus goes without opposition from Li Mi.

Meanwhile, however, when Li Yuan arrives near Hedong, his army is bogged down by the weather, and with food running out, there are rumors that Eastern Tujue and Liu Wuzhou will attack Taiyuan.

Li Yuan initially orders retreat, but at the earnest opposition by Li Jiancheng and Li Shimin, continues to advance.

After defeating Sui forces at Huoyi (also in modern Yuncheng), he decides to leave a small contingent to watch over Hedong while advancing across the Yellow River into Guanzhong (i.e., the Chang'an region).

Once he does, he heads for Chang'an himself, while sending Li Jiancheng to capture the territory around the Tong Pass region to prevent Sui forces at Luoyang from reinforcing Chang'an and Li Shimin north of the Wei River to capture territory there.

Meanwhile, his daughter has also risen in rebellion in support of him, and she is able to gather a sizable army and capture some cities.

She joins forces with Li Shimin and her husband Chai Shao.

Soon, Li Yuan reconsolidates his forces and puts Chang'an under siege.