The accession year of Sundara Coḹa is fixed as 957 CE based on the astronomical data available in his inscriptions. His records are available till his 17th Regnal year. Inscriptions from Tirumālpuram (S.I.I III, 117 & 118), Nemali (139 of 1942-43), Allūr (377 of 1903) and Tirumalavāḍi (2 of 1920) are bearing the 17th Regnal year. The Koyil Devarayan pettai inscription (230 of 1923) refers his 17th regnal year, but mentions the 19th regnal year of Madhurai Koṇḍa Mārāyar. If Madhurai Koṇḍa Mārāyar referred in this inscription is Sundara Coḹa himself, then it should be accepted that He ruled for 19 years. Hence it can be concluded that Sundar Coḹa died on 973 CE or 975 CE. But it is inappropriate to claim that the 19th regnal year inscription quoted in the 17th regnal year belongs to Sundara Coḹa. I think the conclusion of Sri. N.Sethuraman is baseless and the inscription belongs to the period of Parāntaka I.
Regarding the accession date of Uttama Coḹa, we need the Tiruviḍaimaruḍur record (265 of 1907), which possess Kali year 4083 and 13th regnal year. The text of the record in “Svastiśrī Kaliyuga varuṣam Nālāyitteṇpat(tu Mūṉṙu) Uttama Coḹarākiya Kōpparakecari Panmaṙku yāṇḍu ௰(௩) āvadu…” The Kali year is 4083 and the regnal year is 13. Sri. N.Sethuraman (Early Cholas, Mathematics reconstructs the chronology, Page 11) worked on it and pointed out that the inscription mentions the Gata(expired) kali varṣa and not the current year. He added the argument on the basis of Uyyakkoṇḍān Tirumalai record which gives the Kali year as 4080 and Śaka year as 901. On the basis of other records, he concluded that Uttama Coḹa came throne on 971 CE.
But here we face a problem. Tiruvālaṅkāḍu plates of Rajendra I, give another picture. The 69th verse of the plate is as follows.
प्रबलकलिबलान्धध्वान्तविध्वंसहेतोः स्वयमरुण्मॊऴिवर्म्मा प्रार्थ्यमानः प्रजाभिः।
अचकमत न राज्यं स्वे पितृव्ये स्वदेशप्रणयिनि मनसापि क्षत्रधर्म्मार्थवेदी।।
svayamaruṇmŏḻivarmmā prārthyamānaḥ prajābhiḥ|
acakamata na rājyaṁ sve pitṛvye svadeśa
praṇayini manasāpi kṣatradharmmārthavedī||
The meaning of the verse is as follows.
“(Though) requested by the subjects (to occupy the Coḹa throne), in order to destroy the persistently blinding darkness of the powerful Kali (age), Aruṇmoḹivarman who understood the essence of royal conduct, desired not the kingdom for himself even in (his) mind, while his paternal uncle coveted his (i.e Aruṇmoḹi varman’s) dominions.
Quoting the above verse scholars opined that, after the demise of Āditya II, sundara Coḹa died and after his demise, Aruṇmoḹivarmā, who became a great emperor with the name “Rājarāja”, gave up his right and paved way for Uttama Coḹa to come to the throne.
Here arises the problem. Uttama Coḹa ascended the throne during 971 CE. Sundara Coḹa died during 973 CE. Then it is not acceptable to claim that Uttama ascended throne after the demise of Sundara Coḹa.
The possible solution is thus : “Uttama was treated with high respect during the reign of Sundara Coḹa which is ascertained by the Tiruvoṙṙiyūr record of the latter. The text is as follows.
Line 1 : Svastiśrī Madirai Koṇḍa Kōvirācakē
Line 2 : cari Paṉma[r]kku Yāṇḍu Aiñcāvatu Uḍaiyār
Line 3 : Uttama Coḹa devar[r]uḍan vanda
Line 4 : Kaleśi Peruntarattuc ciṅgamayyan magaṉ
Line 5 : Kaḍuttalai Nāgamayyaṉ Tiruvoṙṙiyūr
Line 6 : Mahādevarkku ācantriratāramum Oru Nandā
Line 7 : Viḷakkerippadaṙku vaitta Cāvā mūvā Pērā
Line 8 : ḍu Toṇṇūṙu īḹaviḷakku oṉṙu. Idu Panmā
Line 9 : heśvara rakṣai.
Here Uttama Coḹa is prefixed with a respectful term “Udaiyār”. Though Āditya II was alive during this inscription, Uttama was referred with a respectful term which was usually used for “prince”. Though the term was used to mention some of the local chieftains, this proper usage of the term implies that he was treated as a prince.
Hence it can be concluded that Uttama Coḹa was crowned as prince in 971 CE while Sundara Coḹa was the king. After the demise of the latter, the subjects requested Rājarāja to accept the kingdom. Since Uttama was announced as the prince, Rājarāja, the knower of the royal dharma, didn’t accept the offer. The phrase “Kṣatra-dharmārtha-vedi” clearly gives the implied meaning that he followed the rule and allowed the crowned prince to continue with his rule.
The another interesting point is that Uttama Coḹa ruled for 16 years and hence his rule was ended in 987 CE. Rājarāja ascended the throne in 985. So it is very clear that Rājarāja was made prince in 985 CE and became a full-fledged king in 987 CE. So he started his digvijaya (conquering of the quarters) started after the demise of Uttama Coḹa. This is ascertained by the next verse of Tiruvālaṅgāḍu plates.
त्रिजगदवनदक्षमम्बुजाक्षं स्वयमवतीर्णममुन्निरूप्य चिह्नैः।
अरुण्मॊऴिमभिषिच्य यौवराज्ये धरणिधुरं मधुरान्तको बभार।। 70
trijagadavanadakṣamambujākṣaṁ svayamavatīrṇamamunnirūpya cihnaiḥ|
aruṇmŏḻimabhiṣicya yauvarājye dharaṇidhuraṁ madhurāntako babhāra|| 70
“Having ascertained by the marks (on his body), that Aruṇmoḹi was the lotus-eyed (Viṣṇu) himself, the able protector of the three worlds, that had incarnated (on earth), Madhurāntaka installed him in the office of heir-apparent and (himself) bore the burden of (ruling) the earth.
Aruṇmoḹi varmā took the title “Rājarāja” only from his third regnal year. This must be the reason behind that.