you're fine until 450.
since AB really doens't change zones for you..you can just leave it in Kalimdor or Eastern Kingdoms and not worry about anything.
1-525 can be done in either Kalimdor or EK
300-375+ can be done in Kalimdor, EK or Outland -- Outlands open at 300.
375-450+ can be done in Northerend -- Northerend opens at 375...you probably don't really want to go there on a lvl 70..as most places would be tough, unles you're super geared
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at 451, you unlock new areas in Kalimdor and EK, where you would not want to go on your lvl 70 toon.
so basically..i would let it auto-train to 450, and stay in EK for the whole part, as it's least buggy.
dwarf, troll, night elf and fossil are lower level Azeroth fragments..at around 300 or even 375 you can also start getting nerubian pieces.
if you're looking for specific orc or drainei peieces..then you will need to head off to outlands.
vrykul is in northerend.
tol'vir is the lvl 84-85 in uldum
problem is that at 451, you unlock the sites in twilight highlands and such, where you're too low to really go...which you can try to blacklist
but..there's really no reason to train past 450...you still get xp, and have a chance to get all the rares for everything but tol'vir.