The Tiruneḍuntāṇdakam ('The Long Tāṇdakam') is the work of Tirumaṅgai Āzhvār (Maṅgayarkkarasiyar, also known as Parakāla), the most prolific of the twelve Āzhvārs, whose six prabandhams together comprise nearly a quarter of the entire Nālāyira Divya Prabandham. The tāṇdakam is a specific metrical form used in Tamil devotional literature; the 'neḍu' (long/tall) in the title indicates the extended syllabic length of this form as compared to the shorter Siriya Tāṇdakam, which Tirumaṅgai Āzhvār also composed. Together they are called 'Irandu Tāṇdakam' (the two Tāṇdakams) and form an important pair within his corpus.
The Tiruneḍuntāṇdakam consists of 30 pāsurams and takes the form of a passionate address to Bhagavān as He dwells in various celebrated Divya Desams — including Śrīraṅgam, Tiruveṅkaṭam (Tirupati), Śrī Vaikuṇṭham, and others. Each pāsuram characteristically opens with a vivid description of the kṣetra and the divine form of the Lord enshrined there, before moving into an expression of viraha (separation-longing) and the Āzhvār's all-consuming desire for union (prāpti). This structure of 'sthala varṇanam + viraha ārti' gives the prabandham its distinctive dual character: it functions simultaneously as a pilgrimage guide to the sacred geography of Bhagavān's manifestations and as an intimate record of the Āzhvār's own inner life of longing.
Theologically, the Tiruneḍuntāṇdakam is significant for its articulation of the Āzhvār's experience in the mode of a nāyikā (a female protagonist longing for union) — a convention shared with several other prabandhams but given particular intensity here. The Āzhvār describes himself in feminine terms, overcome by love, unable to sleep, his very body weakened by the fever of viraha. Āchāryas of the tradition have read this as an expression of the ātman's fundamental position before Bhagavān — the jīva is always the feminine principle to Bhagavān's masculine principle, the śeṣa to His śeṣī, the beloved to His supreme lord. The prabandham thus encodes in lyrical form the theological relationship between the individual soul and Bhagavān as understood in Viśiṣṭādvaita. The Tiruneḍuntāṇdakam is regularly recited in Śrī Vaiṣṇava temples and households as part of the Nālāyira Divya Prabandham tradition.