《资治通鉴·唐纪·唐纪六十二》
后来，可汗多次侵扰边境，苗缜一直未能成行。
既而可汗屡侵扰边境，缜竟不行。
Later, the Khan repeatedly harassed the border, and Miao Zhen was never able to set off.
<s>[INST] Kindly elucidate the central themes in this passage in English: 既而可汗屡侵扰边境，缜竟不行。 [/INST] Later, the Khan repeatedly harassed the border, and Miao Zhen was never able to set off.</s>
Kindly elucidate the central themes in this passage in English: 既而可汗屡侵扰边境，缜竟不行。
user
Later, the Khan repeatedly harassed the border, and Miao Zhen was never able to set off.
assistant