Fact: Wolfriders do not count time.
Due to the "Now of Wolf Thought" they have a rather bad concept of time. They remember seasons, bad and good ones - maybe back for some eights. They remember special events - the Allo attack, the year of the snakes, Madcoil. And they remember birth and death of "special" elves - at least who was born before/after someone else. But they do not have a clear defined memory HOW many time passed between these events.
Fact: Wolfriders count their chiefs.
The chiefs line is sort of a timeline for them. And the lifetime and chieftime of the chief is somewhat important for them - memorable. But once again - they have no clearly defined time span - just sort of comparism.
Fact: Wolfriders have Howls and Dreamberries to support their memory.
They do not just forget about everything due to "Now of Wolf Thought" - they remember what the storyteller is passing down on them - generation for generation. The storyteller is sending in the Howls - and I think in sending he gets through at least an imagination of the time passing. Not as an absolute fact ... but in comparism.
I imagine it this way:
In sending you can get an imagination of the person's age - his experiances, the many seasons that passed, the births and deaths he lived to see. Not as a number - but as a good comparism to your own lifespan.
And then Half-Ear, the old storyteller, starts - evoking an event long ago - sending impressions of the time passing:
Moonhowl, our former Howlkeeper, who died as an old elf when I had seen hardly three eights of eights, told me about a sabertooth hunt that occured when she was just a cubling. Chieftess Skyfire, who had seen many seasons already and outlived many of her agemates ...
You get an idea what I mean? The imagination of time passing depends to a good deal on the lifetime of the elf who can pass these memories - and those who listen. Halfear can pass down more or less his lifespan - and the lifespan of Moonhowl, who had passed it down on him in sending to give an impression of age and time.
As long as the Wolfriders had Immortals among them, they might have had a comparably clear knowledge how much time passed between two chiefs - at least some purebloods have outlived several of them.
When they died out there were only the comparably short living Wolfriders - old and young, long and short became more relative.
Let's say Tanner was extremely long living - for said reasons. He would have outlived all his agemates, maybe several generations of tribe member - even in comparably peaceful times there is reason enough for shortcut lives. He was old ... very old compared to his living tribemates. He can pass down an imagination of his long lifespan - but how clear can it be?
Think of yourself - when you are 30 ... can you really imagine how long 200 years are? And when an elf is 300 years ... would he be able to capture how long 2000 years are? Tanner was old ... older than any other elf could imagine - less had lived at least a noteworthy part of this timespan.
The years to come were harder - elves died even earlier in average, including the chiefs. The 2000+ years of Tanner, the oldest elf remembered so far, shrink in comparism. Being the oldest ... becomes about 1000 years (might make 800 years of chieftime).
And then Bearclaw is born ... he outlives agemates, lifemates and children, living for 1000 years and more. (Let's make Longreach and Longbranch relatives, okay?) In the memory of the living Wolfriders he IS the oldest living Wolfrider ever - simply for the reason that they can imagine his lifespan pretty well.
There are still elves who remember Howlings where a long deceased tribemate told the story how she witnessed Bearclaw's birth. While the memory of Tanner's real lifespan is foggy ... they knew he was "very old", but there is no comparism anymore.
Does this make any sense for you?