The word is "often"
I've looked at the document here and throughout it is a common error. "Often" is written "of ten" is numerous places.

HTH!

Here is the information:

http://cnx.org/contents/[email protected]:QYIPjLBA@4/Foreword
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a-comprehensive-outline-of-world-history-organized-by-region-2.1.pdf
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6.6 The Far East: 1500 to 1000 B.C.15 6.6.1 THE FAR EAST Back to The Far East: 3000 to 1500 B.C. (Section 6.5) 6.6.1.1 CHINA AND MANCHURIA (Shang Dynasty until about 1,122 B.C., then Chou) About 1,500 B.C. China passed abruptly from the Neolithic state to a full bronze age, probably getting bronze-working technique from the Near East or Thailand, as the Chinese scholars claim. China received its first farm-yard poultry as the domesticated jungle fowl from the Malayan peninsula. (Ref. 222 ([296])) The first historical dynasty, the Shang, as noted in the last chapter, was a powerful political regime controlling most of northern China, even though in actuality it was a loose confederation of clan domains, many little more than village settlements. Two of their six capitals, at Cheng-chou and An-Yang, have been excavated, the latter showing a Black Pottery Culture. The people were basically Chinese, but some think that the aristocratic, charioteer warrior leaders may have come from farther west in the steppes. They used compound bows and bronze weapons. Fortifications dating to 1,300 B.C. along the Yellow River have evidence of these same warrior bands who may have originated on the Iranian plateau and moved step by step from oasis to oasis, conquering the Neolithic societies in their way. This was an aristocratic age with a sharp cleavage between noble warriors and helpless peasants. A recent newspaper article reports that Chinese scientists have uncovered the remains of 1,000 slaves killed as human sacrifices near An-Yang. Supposedly these were sacrificed for funerals or to honor the ancestors of the nobility, all demonstrating the extreme cruelty and barbarity of the slaveowning nobility of this Shang Dynasty. The religion was a mixture of ancestor and nature worship and their script was ideographic and strictly Chinese. About 1,200 B.C. iron was used in its meteoric form and treated like a semi precious stone. It was ***of ten*** mounted in bronze fittings for ceremonial weapons. (Ref. 136 ([187]), 235 ([313]))


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Note added at 1 hr (2016-11-22 02:12:05 GMT)
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Evidence of this is detailed below (from the same document):

- Clearing land was difficult and was done chiefly by burning. Their staple food
was maize, **of ten** with several varieties grown in the same field.

- These people are dolichocephalic while most American Indians are brachycephalic; their complexions are fair and their hair **of ten** soft and brown, rather than Mongolian coarse and black.

- Another coast road ran absolutely straight for miles on end. These roads averaged 20 feet in width, were **of ten ** paved with stone or cut through rock and many deep chasms were bridged. Nothing in Europe compared to these roads from the time of the Romans until the era of Napoleon. (Ref. 8 ([14]), 10 ([18]))


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Note added at 1 hr (2016-11-22 02:21:28 GMT)
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See Section 6.7, Page 104 (“often” is written “of ten”)
A Comprehensive Outline of World History - UFDC Image Array 2
ufdcimages.uflib.ufl.edu/AA/00/01/16/99/00001/WorldHistory.pdf
6.7 The Far East: 1500 to 1000 B.C. . ......

Examples:
- If the reader is not already well versed in the essential landmarks of the world’s factual history, understanding is **of ten** difficult. (page 15 of PDF file).
- It is well known that the English **of ten** use a "k" where Americans use "c" as in such words as "Keltic"-"Celtic" and "Khosru-"Chosroes", etc. (page 17 of PDF file).