Why did fighting on the Eastern Front end in World War 1?

Fighting on the Eastern Front ended in World War I primarily due to the signing of the Treaty of Brest-Litovsk in March 1918, which followed the Russian Revolution and the Bolsheviks' rise to power. Russia's withdrawal from the war allowed Germany to shift its focus to the Western Front, as the Eastern Front had become untenable for the Russian Empire due to military defeats and internal upheaval. The treaty marked a significant territorial loss for Russia but facilitated a temporary peace in the east, which allowed the Central Powers to consolidate their efforts elsewhere.