Det finns två konstateranden; den ena att de korrumperandes liksom Saruman i öst och startade kulter och den andra att de var aktiva i öst i kampen emot Sauron och att det var en viktig faktor bakom att Han aldrig lyckades skicka större härar emot Väst;
Citera:
I really do not know anything clearly about the other two – since they do not concern the history of the N.W. I think they went as emissaries to distant regions, East and South, far out of Númenórean range: missionaries to 'enemy-occupied' lands, as it were. What success they had I do not know; but I fear that they failed, as Saruman did, though doubtless in different ways; and I suspect they were founders or beginners of secret cults and 'magic' traditions that outlasted the fall of Sauron.- Letter 211
Their task was to circumvent Sauron: to bring help to the few tribes of Men that had rebelled from Melkor-worship, to stir up rebellion ... and after his first fall to search out his hiding (in which they failed) and to cause [?dissension and disarray] among the dark East ... They must have had very great influence on the history of the Second Age and Third Age in weakening and disarraying the forces of East ... who would both in the Second Age and Third Age otherwise have ... outnumbered the West.- HoME 12; Late Writings
(engelska källor eftersom jag mest diskuterar Tolkien på engelska och håller mig till originalspråk)