As I discuss in this question, the Isha Upanishad has a special property that other Upanishads don't: it's part of the Samhitas of the Vedas. In any case, here's the first verse of the Isha Upanishad:
īśā vāsyam idam sarvaṁ
yat kiñca jagatyāṁ jagat
tena tyaktena bhuñjīthā
mā gṛdhaḥ kasya svid dhanam
Whatsoever changeable is in this world, all this is fit to be indwelt, by the Lord. With that (World) renounced enjoy. Covet not anyone's wealth.
Now in this excerpt from his commentary on the Isha Upanishad, the Sri Vaishnava Acharya Vedanta Desikan discusses the question of what the word "Isha" or Lord refers to in this verse. As a Sri Vaishnava, Vedanta Desikan believed that Ishwara or Saguna Brahman (who is the highest Brahman according to Sri Vaishnavism) is the same as Vishnu.
So Vedanta Desikan interprets the word "Isha" as referring to Vishnu, and he spends some time refuting rival theories. First he refutes the notion that Isha refers to Shiva here. Then he refutes the notion that the word Isha is a moving target, referring to a different Lord in every age:
(If it be said that instead of one perpetual All-lord, we may have one Ishvara-stream, one All-Lord in one cosmic age and another in another age and so on, or else we may have several Ishvaras, rulers, at the same time and at all times eternally, but who divide their absolute lordship between themselves by limiting their powers to specific regions, we reply)
But the theories of Ishvara-stream and multiple Ishvaras are rejected by a number of (scriptural) sources of right knowledge, which establish the Lord existing at all three times (past, present and future) and destining all processes.
The notion of different gods controlling different domains is understandable. But my question is, what sect of Hinduism believes that there is an "Ishwara-stream" and that in every cosmic age there is a different supreme lord of the Universe?
Note that I'm only interested in sects that existed in the time of Vedanta Desikan or earlier. Also, what is this "Cosmic age" the passage is speaking about? How often does the "Ishwara stream" produce a new Ishwara? Once a Kalpa, once a Mahakalpa, or what?