The reason of 1 is that these two countries are vassals of the Central Plains Dynasty and need to pay tribute to the Qing Dynasty every year. It can be said that at that time, because these two countries had very good attitudes towards the Qing Dynasty, they all regarded themselves as courtiers, so the rulers of the Qing Dynasty did not send troops to attack. At that time, the rulers of the Qing Dynasty saw that these two countries would give themselves a lot of gold, silver, jewelry and other resources every year, and thought it unnecessary to attack these two countries.
We must know that a war has costs, even a small war will have casualties, but this peaceful way can preserve the country's strength and achieve the purpose that the Qing Dynasty wanted at that time. At that time, the Qing Dynasty occupied other countries in East Asia mainly because these other countries were not as friendly as these two countries, so the Qing Dynasty sent troops to attack other countries.
The second reason is that the Qing army did not have time to attack these two places at that time. You know, at that time, there were often some ambiguous situations in the Qing Dynasty, so most of the Qing army was used to suppress the uprising. It can be said that due to some internal contradictions, the rulers of the Qing Dynasty were unwilling to expand their own territory, because the management cost was high after all, and it would take more energy to manage if they wanted to occupy some land. At that time, the rulers of the Qing dynasty must have wanted to manage the country at that time in order to continuously expand their territory. If they blindly expand their territory, they will only make internal contradictions more and more fierce.