《资治通鉴·唐纪·唐纪四十九》
而且，云南长期遭受吐蕃欺压的屈辱，如今若还不乘这一时机，依靠大国的力量，来报复怨仇，洗雪耻辱，后悔也来不及了。 
且云南久为吐蕃屈辱，今不乘此时依大国之势以复怨雪耻，后悔无及矣。 
In fact, Yunnan has suffered from Tufan oppression for a long time. If you do not take advantage of this opportunity to ally with a powerful nation to exact revenge and wipe away the shame, you will regret it when it is too late.
<s>[INST] Identify the key themes in this Classical Chinese text and explain them in English: 且云南久为吐蕃屈辱，今不乘此时依大国之势以复怨雪耻，后悔无及矣。  [/INST] In fact, Yunnan has suffered from Tufan oppression for a long time. If you do not take advantage of this opportunity to ally with a powerful nation to exact revenge and wipe away the shame, you will regret it when it is too late.</s>
Identify the key themes in this Classical Chinese text and explain them in English: 且云南久为吐蕃屈辱，今不乘此时依大国之势以复怨雪耻，后悔无及矣。
user
In fact, Yunnan has suffered from Tufan oppression for a long time. If you do not take advantage of this opportunity to ally with a powerful nation to exact revenge and wipe away the shame, you will regret it when it is too late.
assistant