Odie the monk, don't be fooled that Menelick the butcher created the relationship, the travels, the trades that exist between central, southeast and West of Ethiopia. No he did not create these relationships. They existed long before him. Gurage traded and intermarried with all of them for millenia before him. Gurage travellled to Oromo markets and bought and sold items of importance, the same with Hadiya and Kembata.
What he did is that he forced all the above to pay him tax on their agricultural produce, on their businesses, on their ancestral lands. He did not add value to their lives. He rather reduced their freedoms and humanity. He indeed impoverished them. They became poorer than they were before his imposition of his imperial rule over them.