FWP:
SETS == A,B; INEXPRESSIBILITY
IDOL: {8,1}
'UNION': {5,2}
VOWS: {20,2}
For background see S. R. Faruqi's choices. For more on Ghalib's unpublished verses, see the discussion in {4,8x}.
The striking first line does seem to invite a historical/political reading of the kind that Gyan Chand gives it: 'Alas, for the good old days of the Mughal Empire!'. And at first the second line seems to cooperate-- right up to the enjoyably multivalent word ʿahd in the middle of the line. Up to that point, given the references to 'Hindustan' and a 'throne' and 'magnificence and grandeur', we can indeed decide to read ʿahd as 'time, era, reign'.
But then when we encounter the phrase ʿahd-e viṣāl-e butāñ , our minds are shunted off in a different direction. For in the world of the ghazal, 'union' is far more likely to be connected with a (probably unfulfilled) 'vow' rather than with a whole 'era' of maximum access to the beloved(s). (How could the lover possibly sustain such bliss for a whole 'era'?) And surely the verse doesn't mean to say that the glory of the Mughal Empire was as untrustworthy as a promise of 'union' from the fickle beloved? Or that its heyday was as notoriously brief as any bliss that she might almost inadvertently have vouchsafed? Or that the Emperor was like a two-timing beloved?
Thus the pleasures of an 'A,B' verse like this. Instead of reading it as a verse in which the first line is central and the second line is an exclamatory description of it, we are led to read it more enjoyably as a verse in which the second line is central and the first line is an exclamatory description of it.
For fortunately, we have {138,6}, which guides us in the right direction: it suggests that the heart of the present verse is indeed an attempt to capture the inexpressible glory of the 'vow of union of idols' [ʿahd-e viṣāl-e butāñ]. If the beloved promises the lover 'union', his ecstasy is beyond all description-- all of Hindustan (the homeland of idols) is nothing but a mere shadow of a rose (when he has a promise from the real rose) at the foot of the throne to which he finds himself elevated in his bliss. (And/or perhaps there's even a brief shining moment, a 'time of union'; but of course it can't last.)
Nazm says about {138,6}, 'The special feature of Hindustan is that in the shadow of
a wall there is darkness, and Hindustan too is a black [kālā]
country' (148). As Asi notes, the present verse too shares this imagery (Hindustan, wall, shadow). For discussion of this imagery, see {138,6}.
Asi:
The shade/shadow or a rose was, so to speak, Hindustan; and that very Hindustan was at the foot of our sitting-platform. Alas, why even ask about the kingship of that time, when we obtained union with the idols! That is, when we obtained union with the idols, then, so to speak, we were a king. And the shade/shadow of the rose and the garden in which we used to sit, was the foot of our sitting-platform. He has called the shade/shadow of the rose 'Hindustan' because of its darkness and blackness.
== Asi, p. 205