Sumitrā as we know was one of the three chief queens of Kosalan King Daśaratha and was the mother of Lakṣmaṇa and Śatrughna.
What we don't know is where was she really from? Wikipedia and other websites say that she was from the Kāśī kingdom , but Kālidāsa in his Raghuvamśam says that she was the daughter of the king of Magadha hence she was a Māgadhī Princess.
So , where was she really from?
Both Raghuvaṁśa and Ānandarāmāyaṇa, are on agreement regarding where Sumitrā was from.
tamalabhanta patiṁ patidevatāḥ śikhariṇāmiva sāgaramāpagāḥ /
magadhakosalakekayaśāsināṁ duhitaro'hitaropitamārgaṇam //
~ Raghuvaṁśa (9.17)
Here, Daśaratha's wife Sumitrā is said to be the daughter of the Rājā of Magadha.
tato rājā daśarathaḥ sumitrāṁ magadheṣajām /
vivāhenāparāṁ patnīṁ cakāra dayitaṁ priyām //
~ Ānandarāmāyaṇa (1.70)
Similarly, it's said here that Daśaratha had vivāha with Sumitrā, who was from Magadhadeśa.
In Rāmāyaṇamīmāṁsā (p. 377), Karapātrī Svāmī refers to Kṛttivāsa Rāmāyaṇa and Asamīya Rāmāyaṇa, as per which, Sumitrā was from Siṁhaladeśa, but he dismisses these, because both these folk Rāmāyaṇa retellings aren't prāmāṇya sources for itihāsa, like say Vālmīki Rāmāyaṇa.
I would be giving a rough eng. transl. of the underlined portion-
According to Kṛttivāsa (1.26), Rājā Sumitra of Siṁhala sent an invitation of her daughter's vivāha Sumitrā, to Daśaratha. ..
According to Asamīyā Rāmāyaṇa Bālakāṇḍa (adhyāya 11), Sumitrā was the daughter of Rājā Sumitra of Siṁhaladeśa.
In Rāmāyaṇa Mīmāṁsā (p. 286-287), Karapātrī Svāmī has argued that Ānandarāmāyaṇa is prāmāṇya, and that it's an aṅga of śatakoṭipravistara Rāmāyaṇa itself. Therefore, there shouldn't be any doubt regarding the information it gives regarding Sumitrā.
Furthermore, in Rāmāyaṇa Mīmāṁsā (p. 378), Karapātrī Svāmī also states that- regarding the caritra of Daśaratha, only the kathās from Vālmīki Rāmāyaṇa,
Adhyātma Rāmāyaṇa, Ānanda Rāmāyaṇa, and Raghuvaṁśa, are prāmāṇya and mūla. Rest of the kathās are retellings, which are based on these, some endowed with creative imaginations of the people.
Or after passage through several sources, vikṛtis have added up within them.
Thus, Sumitrā was from Magadhadeśa, without doubt.
