Original: Ethiopian isolationism ended following a British mission that concluded an alliance between the two nations; however, it was not until 1855 that Ethiopia was completely united and the power in the Emperor restored, beginning with the reign of Emperor Tewodros II.
Simplified: Ethiopian isolationism ended following a British mission that made friendship between the two nations; however, it was not until the reign of Tewodros II that Ethiopia began to take part in world matters once again.