Where Buddha got knowledge?

Buddhists believe that life is both endless and subject to impermanence. This helps to ward off suffering and uncertainty. This state of mind is called as tilakhana. These are also the three signs of existence. This existence phase is endless, and individuals are reincarnated again and again. They experience suffering throughout their lives. However, the state is neither good nor bad as if cannot last forever. Lord Buddha attained all this knowledge under a Bodhi tree. He is believed to have meditated and attained enlightenment. He also realized that there were many Buddhas before him and similar will be in the future.
After spending 49 days of his life under this Bodhi tree, he too became Buddha Gautama and attained enlightenment. By resisting the temptations of Mara, he was able to open the path of enlightenment and salvation.