With no explanation, label text_A→text_B with either "DON'T KNOW", "NO" or "YES".
text_A: Between 1853 and 1862, there were a number of uprisings against the Brooke government but all were mostly contained with the aid of local tribes. To guard against future uprisings, a series of forts were constructed to protect Kuching, including Fort Margherita, completed in 1871. By that time Brooke's level of control over Sarawak was such that defences were not only warranted, but feared to be insufficient.
text_B: As the 1870's began, does it sound like Brooke's alliances with the local tribes appeared to be stable and reliable?
NO.