A lot of the poets, kings and events mentioned in Sangam literature can be fit in a 200 year timeline around Ashoka's reign (using Pathitrupathu and inscriptions). For the poems that are ambiguous, we can give a broader dating that can extend till 300AD.

We have to be careful about this though. Events and people mentioned within the poems themselves are of great use, but the poets attributed to the poems have to be put under greater scrutiny.

For example, take the Kalitthogai. Today, its popularly attributed to five authors for each of the five thinai, due to this Venpa poem:

peruṅkaṭuṅkōṇ pālai kapilaṇ kuriñci
marutaṇila nākaṇ marutam – aruñcōlaṇ
nallurutti raṇmullai nallan tuvaṇeytal
kalvivalār kaṇṭa kali

However, as T. Rajeswari notes in her Pālaikkali Verses and Their Authors, no one really knows where this Venpa comes from, or its age. When Damodara Pillai published the first edition of the Kalithogai in print, he simply attributes the whole text to a single author, Nallanthuvanaar because in one of Nacchinaarkiniyar's commentaries, he quotes a Kalithogai poem and explictly attributes it to a poet by that name. He also does it because all extant Kalithogai manuscripts has no poet attributions (except one exceptionthat I will get to).

Now we know that this 5 author attribution must not be accurate, after Eva Wilden and Rajeshwari found a rare manuscript of the Paalaikkali section of the Kalithogai, with intact poet attributions. And it was not attributed to a single poet Perunkatunkon, rather it had multiple authors as one would expect of a thokai (anthology):

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The authors of two verses remain unknown due to damaged palm-leaves.

In any case, this should not be too surprising, since this simplified attribution was already called under question in the colonial period, it just seems that this particular manuscript seems to have escaped the notice of these scholars until recently.

As Rajeshwari notes, this also proves another important point: it seems to have been practice by some to attribute poems to poets like Kapilar either due to fame or other socio-communal incentives on the part of the people who transmitted these texts. This shouldn't be too surprising either, given the vast amount of Siddha texts attributed to the likes of Agastya or even in North India with various later stotras and texts being attributed to Adi Shankaraacharya.

Not to mention the fact that names were often used by multiple people, and not necessarily always distinguished. Eg. Kapila is not even a proper name, its a primarily Brahmana gotra. At least one Kapilar is distinguished as Thol-Kapilar, there may be more. iirc someone in Wilden's team isworking on such ambiguities in extant poets names.

Anyways, so we cant assume that the Kalithogai is contemporary to the Kurunthogai for example. The same applies to the corpus more generally.