11. INTANGIBLE ASSETS

Intangible assets as of December 31, 2016 and 2017 were as follows:

	2016		2017
	RMB		RMB
Intangible asset
Intangible assets to be amortized
Business Relationship (Representing the relationship with the travel service providers and other business partners)	1,815,034,491		1,800,260,144
Technology	696,499,639		713,220,819
Others	131,629,465		187,739,465
Intangible assets not subject to amortization
Trade mark	11,613,475,256		11,613,475,256
Others	22,140,607		180,248,087

	14,278,779,458		14,494,943,771

Less: accumulated amortization
Intangible assets to be amortized
Business Relationship	(175,130,119	)	(420,311,754	)
Technology	(110,511,387	)	(229,246,477	)
Others	(68,368,021	)	(95,069,619	)

	(354,009,527	)	(744,627,850	)

Net book value
Intangible assets to be amortized
Business Relationship	1,639,904,372		1,379,948,390
Technology	585,988,252		483,974,342
Others	63,261,444		92,669,846
Intangible assets not subject to amortization
Trade mark	11,613,475,256		11,613,475,256
Others	22,140,607		180,248,087

	13,924,769,931		13,750,315,921

Finite-lived intangible assets are tested for impairment if impairment indicators arise. The Company amortizes its finite-lived intangible assets using the straight-line method:

Business Relationship		5-10 years
Technology		5-10 years
Others		3-10 years

Amortization expense for the years ended December 31, 2015, 2016 and 2017 was approximately RMB58 million, RMB255 million and RMB391 million respectively.

The annual estimated amortization expense for intangible assets subject to amortization for the five succeeding years is as follows:

		Amortization
		RMB

2018		396,364,608
2019		390,594,774
2020		374,512,943
2021		218,578,855
2022		174,564,565

		1,554,615,745